In deprecated setup.py install, fall back to distutils.

Instead of failing when easy_install isn't present. Closes #3143

Author: jaraco

newsfragments/3143.bugfix.rst

@@ -0,0 +1 @@
+In deprecated setup.py install, fall back to distutils.

setuptools/command/install.py

@@ -63,9 +63,7 @@ def initialize_options(self):
             standards-based tools.
             """,
             see_url="https://blog.ganssle.io/articles/2021/10/setup-py-deprecated.html",
-            # TODO: Document how to bootstrap setuptools without install
-            #       (e.g. by unzipping the wheel file)
-            #       and then add a due_date to this warning.
+            due_date=(2025, 10, 31),
         )
 
         super().initialize_options()
@@ -74,9 +72,7 @@ def initialize_options(self):
 
     def finalize_options(self) -> None:
         super().finalize_options()
-        if self.root:
-            self.single_version_externally_managed = True
-        elif self.single_version_externally_managed:
+        if self.single_version_externally_managed:
             if not self.root and not self.record:
                 raise DistutilsArgError(
                     "You must specify --record or --root when building system packages"
@@ -93,19 +89,6 @@ def handle_extra_path(self):
         self.extra_dirs = ''
         return None
 
-    def run(self):
-        # Explicit request for old-style install?  Just do it
-        if self.old_and_unmanageable or self.single_version_externally_managed:
-            return super().run()
-
-        if not self._called_from_setup(inspect.currentframe()):
-            # Run in backward-compatibility mode to support bdist_* commands.
-            super().run()
-        else:
-            self.do_egg_install()
-
-        return None
-
     @staticmethod
     def _called_from_setup(run_frame):
         """
@@ -139,9 +122,6 @@ def _called_from_setup(run_frame):
 
         return False
 
-    def do_egg_install(self) -> None:
-        raise NotImplementedError("Support for egg-based install has been removed.")
-
 
 # XXX Python 3.1 doesn't see _nc if this is inside the class
 install.sub_commands = [