Fix setuptools 49 test. (fixes mesonbuild#7452)

Author: mensinda

run_meson_command_tests.py

@@ -129,6 +129,10 @@ def test_meson_installed(self):
         os.environ['PYTHONPATH'] = os.path.join(str(pylibdir), '')
         os.environ['PATH'] = str(bindir) + os.pathsep + os.environ['PATH']
         self._run(python_command + ['setup.py', 'install', '--prefix', str(prefix)])
+        # Fix importlib-metadata by appending all dirs in pylibdir
+        PYTHONPATHS = [pylibdir] + [x for x in pylibdir.iterdir()]
+        PYTHONPATHS = [os.path.join(str(x), '') for x in PYTHONPATHS]
+        os.environ['PYTHONPATH'] = os.pathsep.join(PYTHONPATHS)
         # Check that all the files were installed correctly
         self.assertTrue(bindir.is_dir())
         self.assertTrue(pylibdir.is_dir())