Avoid future breakage of setup.py invokations

docs/builds.rst

@@ -147,7 +147,7 @@ pip:
   Latest version by default.
 
 setuptools:
-  Latest version by default.
+  ``58.3.0`` or older.
 
 mock:
   ``1.0.1`` (could be removed in the future).

docs/development/docs.rst

@@ -33,14 +33,14 @@ you may want to verify those changes locally before pushing upstream.
 
 #. create a virtual environment with Python 3.8
    (preferably the latest release, 3.8.12 at the time of writing),
-   activate it, and upgrade both pip and setuptools:
+   activate it, and upgrade pip:
 
    .. code-block:: console
 
       $ cd readthedocs.org
       $ python3.8 -m venv .venv
       $ source .venv/bin/activate
-      (.venv) $ python -m pip install -U pip setuptools
+      (.venv) $ python -m pip install -U pip
 
 #. install documentation requirements
 

readthedocs/doc_builder/python_environments.py

@@ -197,7 +197,10 @@ def install_build_tools(self):
                     'install',
                     '-U',
                     'virtualenv',
-                    'setuptools',
+                    # We cap setuptools to avoid breakage of projects
+                    # relying on setup.py invokations,
+                    # see https://github.com/readthedocs/readthedocs.org/issues/8659
+                    'setuptools<58.3.0',
                 ]
                 self.build_env.run(
                     *cmd,
@@ -477,7 +480,7 @@ def install_core_requirements(self):
             positive='pip<20.3',
             negative='pip',
         )
-        cmd = pip_install_cmd + [pip_version, 'setuptools']
+        cmd = pip_install_cmd + [pip_version, 'setuptools<58.3.0']
         self.build_env.run(
             *cmd, bin_path=self.venv_bin(), cwd=self.checkout_path
         )

readthedocs/rtd_tests/tests/test_celery.py

@@ -593,7 +593,7 @@ def test_build_tools(self, load_config, build_run):
                 mock.call('asdf', 'install', 'python', python_version),
                 mock.call('asdf', 'global', 'python', python_version),
                 mock.call('asdf', 'reshim', 'python', record=False),
-                mock.call('python', '-mpip', 'install', '-U', 'virtualenv', 'setuptools'),
+                mock.call('python', '-mpip', 'install', '-U', 'virtualenv', 'setuptools<58.3.0'),
                 mock.call('asdf', 'install', 'nodejs', nodejs_version),
                 mock.call('asdf', 'global', 'nodejs', nodejs_version),
                 mock.call('asdf', 'reshim', 'nodejs', record=False),

readthedocs/rtd_tests/tests/test_doc_building.py

@@ -1234,7 +1234,7 @@ def test_install_core_requirements_sphinx(self, checkout_path):
         self.assertEqual(self.build_env_mock.run.call_count, 2)
         calls = self.build_env_mock.run.call_args_list
 
-        core_args = self.pip_install_args + ['pip', 'setuptools']
+        core_args = self.pip_install_args + ['pip', 'setuptools<58.3.0']
         self.assertArgsStartsWith(core_args, calls[0])
 
         requirements = self.base_requirements + requirements_sphinx
@@ -1259,7 +1259,7 @@ def test_install_core_requirements_mkdocs(self, checkout_path):
         self.assertEqual(self.build_env_mock.run.call_count, 2)
         calls = self.build_env_mock.run.call_args_list
 
-        core_args = self.pip_install_args + ['pip', 'setuptools']
+        core_args = self.pip_install_args + ['pip', 'setuptools<58.3.0']
         self.assertArgsStartsWith(core_args, calls[0])
 
         requirements = self.base_requirements + requirements_mkdocs