Unify the behavior around the return type when calling super(install).

Author: jaraco

setuptools/command/install.py

@@ -100,9 +100,9 @@ def run(self):
 
         if not self._called_from_setup(inspect.currentframe()):
             # Run in backward-compatibility mode to support bdist_* commands.
-            super().run()
+            return super().run()
         else:
-            super().run()
+            return super().run()
 
         return None