00251: Change user install location

Set values of prefix and exec_prefix in distutils install command
to /usr/local if executable is /usr/bin/python* and RPM build
is not detected to make pip and distutils install into separate location.

Fedora Change: https://fedoraproject.org/wiki/Changes/Making_sudo_pip_safe
Downstream only: Reworked in Fedora 36+ to follow https://bugs.python.org/issue43976

pypa/distutils integration: pypa/distutils#70

Also set sysconfig._PIP_USE_SYSCONFIG = False, to force pip-upgraded-pip
to respect this patched distutils install command.
See https://bugzilla.redhat.com/show_bug.cgi?id=2014513

Co-authored-by: Miro Hrončok <miro@hroncok.cz>

Lib/distutils/command/install.py

@@ -159,6 +159,8 @@ class install(Command):
 
     negative_opt = {'no-compile' : 'compile'}
 
+    # Allow Fedora to add components to the prefix
+    _prefix_addition = getattr(sysconfig, '_prefix_addition', '')
 
     def initialize_options(self):
         """Initializes options."""
@@ -441,8 +443,10 @@ def finalize_unix(self):
                     raise DistutilsOptionError(
                           "must not supply exec-prefix without prefix")
 
-                self.prefix = os.path.normpath(sys.prefix)
-                self.exec_prefix = os.path.normpath(sys.exec_prefix)
+                self.prefix = (
+                    os.path.normpath(sys.prefix) + self._prefix_addition)
+                self.exec_prefix = (
+                    os.path.normpath(sys.exec_prefix) + self._prefix_addition)
 
             else:
                 if self.exec_prefix is None:

Lib/site.py

@@ -380,8 +380,15 @@ def getsitepackages(prefixes=None):
     return sitepackages
 
 def addsitepackages(known_paths, prefixes=None):
-    """Add site-packages to sys.path"""
+    """Add site-packages to sys.path
+
+    '/usr/local' is included in PREFIXES if RPM build is not detected
+    to make packages installed into this location visible.
+
+    """
     _trace("Processing global site-packages")
+    if ENABLE_USER_SITE and 'RPM_BUILD_ROOT' not in os.environ:
+        PREFIXES.insert(0, "/usr/local")
     for sitedir in getsitepackages(prefixes):
         if os.path.isdir(sitedir):
             addsitedir(sitedir, known_paths)

Lib/sysconfig.py

@@ -58,6 +58,22 @@
         },
     }
 
+# Force pip to use distutils paths instead of sysconfig
+# https://github.com/pypa/pip/issues/10647
+_PIP_USE_SYSCONFIG = False
+
+# This is used by distutils.command.install in the stdlib
+# as well as pypa/distutils (e.g. bundled in setuptools).
+# The self.prefix value is set to sys.prefix + /local/
+# if neither RPM build nor virtual environment is
+# detected to make distutils install packages
+# into the separate location.
+# https://fedoraproject.org/wiki/Changes/Making_sudo_pip_safe
+if (not (hasattr(sys, 'real_prefix') or
+    sys.prefix != sys.base_prefix) and
+    'RPM_BUILD_ROOT' not in os.environ):
+    _prefix_addition = "/local"
+
 
 # NOTE: site.py has copy of this function.
 # Sync it when modify this function.