diff --git a/pkgs/sagemath-categories/MANIFEST.in.m4 b/pkgs/sagemath-categories/MANIFEST.in.m4
index b2e35673ec0..585640540e2 100644
--- a/pkgs/sagemath-categories/MANIFEST.in.m4
+++ b/pkgs/sagemath-categories/MANIFEST.in.m4
@@ -28,15 +28,222 @@ exclude sage/categories/sets_with_partial_maps.*
 exclude sage/categories/subobjects.*
 exclude sage/categories/subquotients.*
 exclude sage/categories/with_realizations.*
-# Exclude to make it a namespace package
-exclude sage/categories/__init__.py
 
-include sage/rings/ideal.*
-include sage/rings/ring.*
+include sage/geometry/abc.p*
+
+# Interfaces
+include sage/interfaces/all.p*
+include sage/interfaces/abc.p*
+include sage/interfaces/process.p*                      # needed for sage.parallel
+include sage/interfaces/tab_completion.p*
+include sage/misc/object_multiplexer.p*
+include sage/misc/multireplace.p*
+include sage/interfaces/sagespawn.p*
+include sage/interfaces/quit.p*
+include sage/interfaces/cleaner.p*
+include sage/interfaces/expect.p*
+include sage/interfaces/interface.p*
+include sage/interfaces/sage0.p*
+
+graft sage/parallel
+
 graft sage/typeset                     # dep of sage.categories.tensor
-# include sage/rings/integer*.*     # depends on cypari, flint - https://github.com/sagemath/sage/issues/30022
-# include sage/rings/rational*.*
-# include sage/rings/infinity.*
+
+include sage/groups/generic.p*
+include sage/groups/groups_catalog.p*
+
+include sage/monoids/monoid.p*
+
+include sage/rings/ring.*
+include sage/rings/quotient_ring*.p*
+include sage/rings/homset.p*
+include sage/rings/ideal*.p*
+include sage/rings/noncommutative_ideals.p*
+include sage/rings/localization.p*
+include sage/rings/morphism.p*
+
+include sage/rings/abc.*
+include sage/rings/integer*.p*
+exclude sage/rings/integer_fake.pxd     # in sagemath-objects
+include sage/rings/rational*.*
+include sage/rings/infinity.*
+include sage/rings/factorint.p*
+include sage/rings/sum_of_squares.p*
+include sage/rings/generic.p*
+
+include sage/misc/allocator.*
+include sage/misc/latex*.*
+include sage/misc/html.p*
+include sage/misc/mathml.p*
+include sage/misc/table.p*
+include sage/misc/map_threaded.p*
+include sage/misc/mrange.p*
+include sage/misc/defaults.p*
+include sage/misc/converting_dict.p*
+include sage/misc/parser.p*
+include sage/misc/method_decorator.p*
+include sage/misc/random_testing.p*
+include sage/misc/rest_index_of_methods.p*
+include sage/misc/callable_dict.p*
+include sage/misc/search.p*
+include sage/misc/stopgap.p*
+
+## Data structures
+include sage/misc/binary_tree.p*
+graft sage/data_structures               # bitset needed by sage.graphs and sage.geometry.polyhedron
+exclude sage/data_structures/bounded_integer_sequences.*   # depends on flint
+exclude sage/data_structures/stream.*
+graft sage/groups/perm_gps/partn_ref  # but not partn_ref2, which depends on GAP
+exclude sage/groups/perm_gps/partn_ref/refinement_graphs.p*    # sagemath-graphs
+exclude sage/groups/perm_gps/partn_ref/refinement_matrices.p*  # sagemath-modules
+exclude sage/groups/perm_gps/partn_ref/refinement_binary.p*    # sagemath-modules
+
+
+# These might later go to a separate distribution sagemath-functions (> sagemath-objects);
+# but sage.functions currently depends on basic rings (QQ etc)
+graft sage/arith
+# Exclude what is included in sagemath-objects already
+exclude sage/arith/long.p*
+exclude sage/arith/numerical_approx.p*
+exclude sage/arith/power.p*
+
+include sage/calculus/functional.p*
+include sage/calculus/functions.p*
+include sage/misc/derivative.p*
+include sage/misc/functional.p*
+include sage/symbolic/symbols.p*
+include sage/symbolic/function.p*
+graft sage/functions
+
+
+include sage/rings/finite_rings/element_base.*
+include sage/rings/finite_rings/stdint.*
+include sage/rings/finite_rings/finite_field_base.p*
+include sage/rings/finite_rings/finite_field_constructor.p*
+include sage/rings/finite_rings/finite_field_prime_modn.p*
+include sage/rings/finite_rings/residue_field.p*
+include sage/rings/finite_rings/hom_finite_field.p*
+include sage/rings/finite_rings/hom_prime_finite_field.p*
+include sage/rings/finite_rings/homset.p*
+include sage/rings/fast_arith.*
+include sage/rings/finite_rings/integer_mod_limits.h
+include sage/rings/finite_rings/integer_mod.p*
+include sage/rings/finite_rings/integer_mod_ring.p*
+include sage/rings/finite_rings/conway_polynomials.p*
+include sage/rings/finite_rings/galois_group.p*
+include sage/rings/algebraic_closure_finite_field.p*
+
+include sage/rings/number_field/number_field_base.p*
+include sage/rings/number_field/number_field_element_base.p*
+include sage/rings/number_field/number_field_ideal.p*
+include sage/rings/real_double.p*
+
+include sage/rings/real_lazy.p*
+
+include sage/rings/fraction_field.p*
+include sage/rings/fraction_field_element.p*
+include sage/rings/qqbar_decorators.p*
+
+include sage/rings/padics/padic_generic.p*
+include sage/rings/padics/local_generic.p*
+include sage/rings/padics/local_generic_element.p*
+include sage/rings/padics/precision_error.p*
+include sage/rings/padics/misc.p*
+
+include sage/rings/polynomial/polynomial_ring.p*
+include sage/rings/polynomial/polynomial_ring_constructor.p*
+include sage/rings/polynomial/polynomial_ring_homomorphism.p*
+include sage/rings/polynomial/polynomial_quotient_ring.p*
+include sage/rings/polynomial/polynomial_singular_interface.p*
+include sage/rings/polynomial/multi_polynomial_ring.p*
+include sage/rings/polynomial/multi_polynomial_ring_base.p*
+include sage/rings/polynomial/multi_polynomial_sequence.p*
+include sage/rings/polynomial/multi_polynomial_ideal.p*
+include sage/rings/polynomial/infinite_polynomial_*.p*
+include sage/rings/polynomial/commutative_polynomial.p*
+include sage/rings/polynomial/polynomial_compiled.p*
+include sage/rings/polynomial/polynomial_element.p*
+include sage/rings/polynomial/polynomial_element_generic.p*
+include sage/rings/polynomial/polynomial_fateman.p*
+include sage/rings/polynomial/polynomial_quotient_ring_element.p*
+include sage/rings/polynomial/multi_polynomial.p*
+include sage/rings/polynomial/multi_polynomial_element.p*
+include sage/rings/polynomial/polydict.p*
+include sage/rings/polynomial/term_order.p*
+include sage/rings/polynomial/flatten.p*
+include sage/rings/polynomial/cyclotomic.p*
+include sage/rings/polynomial/laurent_polynomial_ring*.p*
+include sage/rings/polynomial/laurent_polynomial_ideal.p*
+include sage/rings/polynomial/laurent_polynomial.p*                     # but not laurent_polynomial_mpair, which needs Matrix
+include sage/rings/polynomial/ideal.p*
+include sage/rings/polynomial/toy*.p*
+include sage/rings/polynomial/symmetric_*.p*
+## include sage/rings/polynomial/ore*.p*                                   # need for sage.categories.drinfeld_modules
+
+include sage/rings/continued_fraction*.p*
+
+graft sage/rings/function_field
+exclude sage/rings/function_field/*_polymod.*                           # needs Singular
+exclude sage/rings/function_field/derivations*.*                        # module elements
+exclude sage/rings/function_field/differential.*                        # module elements
+exclude sage/rings/function_field/divisor.*                             # module elements
+exclude sage/rings/function_field/hermite_form_polynomial.*             # cimports Matrix
+exclude sage/rings/function_field/valuation*.*                          # ??
+prune sage/rings/function_field/drinfeld_modules                        # needs ore_polynomial etc.
+
+include sage/rings/power_series_mpoly.p*
+include sage/rings/power_series_poly.p*
+include sage/rings/power_series_ring_element.p*
+include sage/rings/power_series_ring.p*
+include sage/rings/multi_power_series_ring.py
+include sage/rings/multi_power_series_ring_element.py
+include sage/rings/laurent_series_ring*.p*
+include sage/rings/puiseux_series_ring*.p*
+
+graft sage/rings/semirings
+
+include sage/rings/tests.p*
+include sage/rings/big_oh.p*
+
+include sage/ext/fast_*.p*
+
+include sage/combinat/integer_vector.p*
+graft sage/combinat/integer_lists
+include sage/combinat/backtrack.p*
+include sage/combinat/combinat.p*
+include sage/combinat/combinat_cython.p*
+include sage/combinat/combination.p*
+include sage/combinat/combinatorial_map.p*
+include sage/combinat/composition.p*
+include sage/combinat/permutation.p*
+include sage/combinat/permutation_cython.p*
+include sage/combinat/ranker.py                                         # for sage.sets.finite_set_map_cy
+include sage/combinat/subset.p*
+include sage/combinat/tools.p*
+include sage/combinat/tuple.p*
+# leave out partition - has complicated deps
+# leave out integer_vector_weighted - needs combinat.words.word
+include sage/combinat/subsets_hereditary.p*
+include sage/combinat/subsets_pairwise.p*
+include sage/combinat/dlx.p*
+include sage/combinat/matrices/dancing_links.p*
+include sage/combinat/matrices/dancing_links_c.h
+include sage/combinat/matrices/dlxcpp.p*
+
+# see src/sage/schemes/generic/notes/imports.txt
+graft sage/schemes/generic
+graft sage/schemes/affine
+graft sage/schemes/projective
+graft sage/schemes/product_projective
+
+graft sage/sets
+exclude sage/sets/pythonclass.*                                 # sagemath-objects
+
+include sage/numerical/backends/generic*backend.p*
+
+## These two should probably go to sagemath-combinat instead.
+# include sage/data_structures/stream.p*
+# include sage/rings/lazy_series*.p*
 
 global-exclude *.c
 global-exclude *.cpp
diff --git a/pkgs/sagemath-categories/pyproject.toml.m4 b/pkgs/sagemath-categories/pyproject.toml.m4
index cf4c97f1fd1..c55a122ea28 100644
--- a/pkgs/sagemath-categories/pyproject.toml.m4
+++ b/pkgs/sagemath-categories/pyproject.toml.m4
@@ -9,6 +9,7 @@ requires = [
     SPKG_INSTALL_REQUIRES_sagemath_objects
     SPKG_INSTALL_REQUIRES_cython
     SPKG_INSTALL_REQUIRES_gmpy2
+    SPKG_INSTALL_REQUIRES_memory_allocator
     SPKG_INSTALL_REQUIRES_cysignals
 ]
 build-backend = "setuptools.build_meta"
diff --git a/pkgs/sagemath-categories/setup.cfg.m4 b/pkgs/sagemath-categories/setup.cfg.m4
index f5eb7c72968..ba987293b76 100644
--- a/pkgs/sagemath-categories/setup.cfg.m4
+++ b/pkgs/sagemath-categories/setup.cfg.m4
@@ -11,6 +11,7 @@ include(`setup_cfg_metadata.m4')dnl'
 python_requires = >=3.9, <3.12
 install_requires =
     SPKG_INSTALL_REQUIRES_sagemath_objects
+    SPKG_INSTALL_REQUIRES_memory_allocator
 
 [options.extras_require]
 test = SPKG_INSTALL_REQUIRES_sagemath_repl
diff --git a/pkgs/sagemath-objects/MANIFEST.in b/pkgs/sagemath-objects/MANIFEST.in
index 98b6910849a..e5ed95278aa 100644
--- a/pkgs/sagemath-objects/MANIFEST.in
+++ b/pkgs/sagemath-objects/MANIFEST.in
@@ -32,6 +32,7 @@ include sage/misc/classcall_metaclass.*
 include sage/misc/inherit_comparison*.*
 include sage/misc/weak_dict.*
 include sage/misc/nested_class*.*
+include sage/misc/test_nested_class*.p*
 include sage/misc/abstract_method.*
 include sage/misc/cachefunc.*
 include sage/misc/decorators.*
@@ -46,42 +47,57 @@ include sage/misc/constant_function.*
 include sage/misc/call.*
 include sage/misc/bindable_class.*
 include sage/misc/namespace_package.p*
-include sage/misc/package_dir.py
 
 include sage/misc/verbose.*
 include sage/misc/repr.*
 include sage/misc/superseded.*
 include sage/misc/misc_c.*              # prod
 include sage/misc/flatten.*             # dep of sage/categories/coxeter_groups.py
-
+include sage/misc/lazy_list.p*
 include sage/misc/lazy_import*.*
 include sage/misc/sageinspect.*          # dep of sage/misc/lazy_import
 include sage/misc/instancedoc.*          # dep of sage/misc/lazy_import
 
 include sage/misc/persist.*
 include sage/misc/sage_unittest.*        # dep of sage/misc/persist
+include sage/misc/fpickle.p*
 
 include sage/misc/randstate.*         # used in sage.doctest
 include sage/misc/prandom.*              # dep of sage/rings/ring
 
 include sage/ext/stdsage.pxd
+include sage/ext/mod_int.*
+include sage/ext/cplusplus.pxd
+include sage/ext/ccobject.h
 include sage/sets/pythonclass.*
 include sage/arith/power.*
 include sage/arith/numerical_approx.*
 # integers...
 include sage/arith/long.*
 include sage/rings/integer_fake.*
-graft sage/libs/gmp
+# coerce actions needs is_Group
+include sage/groups/group.*
+include sage/groups/old.*
 
+# needed for sage.structure.formal_sum
+include sage/modules/module.p*
+
+graft sage/libs/gmp
+include sage/libs/gmpxx.pxd
 
 
 ## What we do not want:
 # sage/misc/latex         -- this should really go to another package
 
 
-## FIXME: Needed for doctesting
+## Needed for doctesting; we keep sagemath-repl pure Python
 include sage/misc/misc.*                # some_tuples used in sage.misc.sage_unittest
 include sage/misc/timing.p*             # walltime, cputime used in sage.doctest
+include sage/misc/globals.p*
+include sage/misc/sage_timeit*.p*
+include sage/misc/session.p*
+include sage/misc/reset.p*
+include sage/misc/sage_ostools.p*
 
 global-exclude all__*.py
 global-include all__sagemath_objects.py
diff --git a/pkgs/sagemath-objects/setup.cfg.m4 b/pkgs/sagemath-objects/setup.cfg.m4
index 894c07b5bbf..db018e05c43 100644
--- a/pkgs/sagemath-objects/setup.cfg.m4
+++ b/pkgs/sagemath-objects/setup.cfg.m4
@@ -22,6 +22,7 @@ test =
 
 [options.package_data]
 sage.cpython =
+    pycore_long.h
     pyx_visit.h
     string_impl.h
     cython_metaclass.h
diff --git a/src/sage/ext/cplusplus.pxd b/src/sage/ext/cplusplus.pxd
index e504f0c9fbb..d748bf2347a 100644
--- a/src/sage/ext/cplusplus.pxd
+++ b/src/sage/ext/cplusplus.pxd
@@ -8,7 +8,7 @@
 #                  http://www.gnu.org/licenses/
 #*****************************************************************************
 
-cdef extern from "sage/ext/ccobject.h":
+cdef extern from "ccobject.h":
     # Print representation of any C++ object
     str ccrepr[T](const T& x)
 
diff --git a/src/sage/libs/polybori/decl.pxd b/src/sage/libs/polybori/decl.pxd
index dd6a3aaf0b6..785e216e3db 100644
--- a/src/sage/libs/polybori/decl.pxd
+++ b/src/sage/libs/polybori/decl.pxd
@@ -23,7 +23,7 @@ cdef extern from "polybori/pbori_defs.h" namespace "COrderEnums":
         greater_or_equal_min    "CTypes::greater_or_equal_min"
 
 
-cdef extern from "sage/libs/polybori/pb_wrap.h":
+cdef extern from "pb_wrap.h":
     cdef cppclass PBNavigator "CCuddNavigator":
         PBNavigator thenBranch()
         PBNavigator elseBranch()
diff --git a/src/sage/misc/all__sagemath_categories.py b/src/sage/misc/all__sagemath_categories.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/sage/rings/all__sagemath_categories.py b/src/sage/rings/all__sagemath_categories.py
index 8d14e7afcda..b76975de3b2 100644
--- a/src/sage/rings/all__sagemath_categories.py
+++ b/src/sage/rings/all__sagemath_categories.py
@@ -1,6 +1,78 @@
 # Ring base classes
-from .ring import Ring
+from .ring import (Ring, Field, CommutativeRing, IntegralDomain,
+    DedekindDomain, PrincipalIdealDomain, EuclideanDomain)
+
+# Ring element base classes
+from sage.structure.element import (CommutativeAlgebraElement,
+        RingElement, CommutativeRingElement, IntegralDomainElement,
+        DedekindDomainElement, PrincipalIdealDomainElement,
+        EuclideanDomainElement, FieldElement)
+
+# Rational numbers
+from .rational import Rational
+from .rational_field import RationalField, QQ
+Rationals = RationalField
+
+# Rational integers.
+from .integer_ring import IntegerRing, ZZ, crt_basis
+from .integer import Integer
+
+# Integers modulo n.
+from sage.rings.finite_rings.integer_mod_ring import IntegerModRing, Zmod
+from sage.rings.finite_rings.integer_mod import IntegerMod, Mod, mod
+Integers = IntegerModRing
+
+# Infinities
+from .infinity import infinity, Infinity, InfinityRing, unsigned_infinity, UnsignedInfinityRing
+oo = infinity
+
+# Quotient
+from .quotient_ring import QuotientRing
+
+# Localization
+from .localization import Localization
+
+# Fraction field
+from .fraction_field import FractionField
+Frac = FractionField
+
+# Function field
+from .function_field.all__sagemath_categories import *
+
+# Double precision floating point numbers
+from .real_double import RealDoubleField, RDF, RealDoubleElement
 
 # Ideals
 from .ideal import Ideal
 ideal = Ideal
+
+# Semirings
+from .semirings.all import *
+
+from .finite_rings.all__sagemath_categories import *
+from .number_field.all__sagemath_categories import *
+from .padics.all__sagemath_categories import *
+from .polynomial.all__sagemath_categories import *
+
+# Power series rings
+from .power_series_ring import PowerSeriesRing
+
+# Laurent series ring in one variable
+from .laurent_series_ring import LaurentSeriesRing
+
+# Puiseux series ring
+from .puiseux_series_ring import PuiseuxSeriesRing
+
+# Big-oh notation
+from .big_oh import O
+
+# continued fractions
+from sage.rings.continued_fraction import (continued_fraction,
+                                           continued_fraction_list)
+
+# Lazy reals
+from .real_lazy import RealLazyField, RLF, ComplexLazyField, CLF
+
+# Preliminary version of real numbers for doctesting without sage.rings.real_mpfr.
+# sage.rings.all redefines it.
+RealNumber = RR = RDF             # used by the preparser to wrap real literals
diff --git a/src/sage/rings/finite_rings/all__sagemath_categories.py b/src/sage/rings/finite_rings/all__sagemath_categories.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/sage/rings/function_field/all__sagemath_categories.py b/src/sage/rings/function_field/all__sagemath_categories.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/sage/rings/integer_ring.pyx b/src/sage/rings/integer_ring.pyx
index c7a05a13e16..c9178fa2ca2 100644
--- a/src/sage/rings/integer_ring.pyx
+++ b/src/sage/rings/integer_ring.pyx
@@ -54,8 +54,6 @@ import sage.rings.infinity
 import sage.rings.rational
 import sage.rings.rational_field
 import sage.rings.ideal
-import sage.libs.pari.all
-import sage.rings.ideal
 from sage.categories.basic import EuclideanDomains
 from sage.categories.infinite_enumerated_sets import InfiniteEnumeratedSets
 from sage.rings.number_field.number_field_element_base import NumberFieldElement_base
@@ -69,7 +67,7 @@ from sage.misc.randstate cimport randstate, current_randstate, SAGE_RAND_MAX
 
 cimport sage.rings.integer as integer
 
-from . import ring
+from sage.rings import ring
 
 arith = None
 cdef void late_import():
diff --git a/src/sage/rings/number_field/all__sagemath_categories.py b/src/sage/rings/number_field/all__sagemath_categories.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/sage/rings/padics/all__sagemath_categories.py b/src/sage/rings/padics/all__sagemath_categories.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/sage/rings/polynomial/all__sagemath_categories.py b/src/sage/rings/polynomial/all__sagemath_categories.py
new file mode 100644
index 00000000000..2b79da92a4c
--- /dev/null
+++ b/src/sage/rings/polynomial/all__sagemath_categories.py
@@ -0,0 +1,21 @@
+# Quotient of polynomial ring
+from sage.rings.polynomial.polynomial_quotient_ring import PolynomialQuotientRing
+from sage.rings.polynomial.polynomial_quotient_ring_element import PolynomialQuotientRingElement
+
+# Univariate Polynomial Rings
+from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
+from sage.rings.polynomial.polynomial_ring import polygen, polygens
+from sage.rings.polynomial.polynomial_element import Polynomial
+
+# Multivariate Polynomial Rings
+from sage.rings.polynomial.term_order import TermOrder
+from sage.rings.polynomial.multi_polynomial_element import degree_lowest_rational_function
+
+# Infinite Polynomial Rings
+from sage.rings.polynomial.infinite_polynomial_ring import InfinitePolynomialRing
+
+# Laurent Polynomial Rings
+from sage.rings.polynomial.laurent_polynomial_ring import LaurentPolynomialRing
+
+# Evaluation of cyclotomic polynomials
+from sage.rings.polynomial.cyclotomic import cyclotomic_value
diff --git a/src/sage_setup/__init__.py b/src/sage_setup/__init__.py
index e69de29bb2d..b494f685f90 100644
--- a/src/sage_setup/__init__.py
+++ b/src/sage_setup/__init__.py
@@ -0,0 +1,103 @@
+def sage_setup(distributions, *,
+               interpreters=(),
+               required_modules=(), optional_modules=(),
+               package_data=None):
+    import time
+
+    from distutils import log
+    from setuptools import setup
+    from sage_setup.command.sage_build_ext_minimal import sage_build_ext_minimal
+    from sage_setup.cython_options import compiler_directives, compile_time_env_variables
+    from sage_setup.extensions import create_extension
+    from sage_setup.find import find_python_sources, find_extra_files
+
+    # Work around a Cython problem in Python 3.8.x on macOS
+    # https://github.com/cython/cython/issues/3262
+    import os
+    if os.uname().sysname == 'Darwin':
+        import multiprocessing
+        multiprocessing.set_start_method('fork', force=True)
+
+    import sys
+
+    from sage_setup.excepthook import excepthook
+    sys.excepthook = excepthook
+
+    from sage_setup.setenv import setenv
+    setenv()
+
+    import sage.env
+    sage.env.default_required_modules = required_modules
+    sage.env.default_optional_modules = optional_modules
+
+    cmdclass = dict(build_ext=sage_build_ext_minimal)
+
+    sdist = len(sys.argv) > 1 and (sys.argv[1] in ["sdist", "egg_info", "dist_info"])
+
+    # ########################################################
+    # ## Discovering Sources
+    # ########################################################
+    if sdist:
+        extensions = []
+        python_modules = []
+        python_packages = []
+        package_data = {}
+    else:
+        if interpreters:
+            log.info("Generating auto-generated sources")
+            # from sage_setup.autogen import autogen_all
+            # autogen_all()
+            from sage_setup.autogen.interpreters import rebuild
+            rebuild(os.path.join("sage", "ext", "interpreters"),
+                    interpreters=['CDF', 'RDF', 'RR', 'CC'],
+                    distribution='sagemath-modules', force=True)
+
+        log.info("Discovering Python/Cython source code....")
+        t = time.time()
+
+        python_packages, python_modules, cython_modules = find_python_sources(
+            '.', ['sage'], distributions=distributions)
+        extra_files = find_extra_files(
+            '.', ['sage'], '/doesnotexist', distributions=distributions)
+        package_data = {"": [f
+                             for pkg, files in extra_files.items()
+                             for f in files ]}
+        package_data.update({})
+        python_packages += list(package_data)
+
+        log.debug('python_packages = {0}'.format(sorted(python_packages)))
+        log.debug('python_modules = {0}'.format(sorted(m if isinstance(m, str) else m.name for m in python_modules)))
+        log.debug('cython_modules = {0}'.format(sorted(m if isinstance(m, str) else m.name for m in cython_modules)))
+        log.debug('package_data = {0}'.format(package_data))
+
+        log.info(f"Discovered Python/Cython sources, time: {(time.time() - t):.2f} seconds.")
+
+        # from sage_build_cython:
+        import Cython.Compiler.Options
+        Cython.Compiler.Options.embed_pos_in_docstring = True
+        gdb_debug = os.environ.get('SAGE_DEBUG', None) != 'no'
+
+        try:
+            from Cython.Build import cythonize
+            from sage.env import cython_aliases, sage_include_directories
+            from sage.misc.package_dir import cython_namespace_package_support
+            with cython_namespace_package_support():
+                extensions = cythonize(
+                    cython_modules,
+                    include_path=sage_include_directories(use_sources=True) + ['.'],
+                    compile_time_env=compile_time_env_variables(),
+                    compiler_directives=compiler_directives(False),
+                    aliases=cython_aliases(),
+                    create_extension=create_extension,
+                    gdb_debug=gdb_debug,
+                    nthreads=4)
+        except Exception as exception:
+            log.warn(f"Exception while cythonizing source files: {repr(exception)}")
+            raise
+
+    setup(cmdclass=cmdclass,
+          packages=python_packages,
+          py_modules=python_modules,
+          ext_modules=extensions,
+          package_data=package_data,
+    )
diff --git a/src/sage_setup/find.py b/src/sage_setup/find.py
index 61d91abc2eb..192f7614776 100644
--- a/src/sage_setup/find.py
+++ b/src/sage_setup/find.py
@@ -151,7 +151,7 @@ def find_python_sources(src_dir, modules=['sage'], distributions=None,
                     dirnames[:] = []
                     continue
                 # Ordinary package or namespace package.
-                if distributions is None or '' in distributions:
+                if distributions is None:
                     python_packages.append(package)
 
                 for filename in filenames: