Feature flag: remove DONT_SHALLOW_CLONE (#10588)

* Feature flag: remove `DONT_SHALLOW_CLONE`

This can be done now by using `build.jobs.post_checkout`.
See an example at https://docs.readthedocs.io/en/latest/build-customization.html#unshallow-git-clone

* Use a different `start_time` to make the API call valid

* Resolve merge conflict

* Solve merge conflict

* Move code to simplify diff

* Remove double space

readthedocs/projects/models.py

@@ -1928,7 +1928,6 @@ def add_features(sender, **kwargs):
     # may be added by other packages
     MKDOCS_THEME_RTD = "mkdocs_theme_rtd"
     API_LARGE_DATA = "api_large_data"
-    DONT_SHALLOW_CLONE = "dont_shallow_clone"
     CONDA_APPEND_CORE_REQUIREMENTS = "conda_append_core_requirements"
     ALL_VERSIONS_IN_HTML_CONTEXT = "all_versions_in_html_context"
     CDN_ENABLED = "cdn_enabled"
@@ -1969,10 +1968,6 @@ def add_features(sender, **kwargs):
             MKDOCS_THEME_RTD,
             _("MkDocs: Use Read the Docs theme for MkDocs as default theme"),
         ),
-        (
-            DONT_SHALLOW_CLONE,
-            _("Build: Do not shallow clone when cloning git repos"),
-        ),
         (
             API_LARGE_DATA,
             _("Build: Try alternative method of posting large data"),

readthedocs/vcs_support/backends/git.py

@@ -148,6 +148,7 @@ def get_remote_fetch_refspec(self):
             )
 
     def clone(self):
+        """Clones the repository."""
         # TODO: We should add "--no-checkout" in all git clone operations, except:
         #  There exists a case of version_type=BRANCH without a branch name.
         #  This case is relevant for building projects for the first time without knowing the name
@@ -268,19 +269,6 @@ def validate_submodules(self, config):
             return False, invalid_submodules
         return True, submodules.keys()
 
-    def use_shallow_clone(self):
-        """
-        Test whether shallow clone should be performed.
-
-        .. note::
-
-            Temporarily, we support skipping this option as builds that rely on
-            git history can fail if using shallow clones. This should
-            eventually be configurable via the web UI.
-        """
-        from readthedocs.projects.models import Feature
-        return not self.project.has_feature(Feature.DONT_SHALLOW_CLONE)
-
     def checkout_revision(self, revision):
         try:
             code, out, err = self.run('git', 'checkout', '--force', revision)