gh-101162: Forbid using issubclass() with GenericAlias as the 1st arg (GH-103369)

Objects/abstract.c

@@ -2812,7 +2812,7 @@ object_issubclass(PyThreadState *tstate, PyObject *derived, PyObject *cls)
         return -1;
     }
 
-    /* Probably never reached anymore. */
+    /* Can be reached when infinite recursion happens. */
     return recursive_issubclass(derived, cls);
 }
 

Objects/genericaliasobject.c

@@ -626,6 +626,7 @@ ga_vectorcall(PyObject *self, PyObject *const *args,
 
 static const char* const attr_exceptions[] = {
     "__class__",
+    "__bases__",
     "__origin__",
     "__args__",
     "__unpacked__",