[commands] Properly load the original module when reloading fails.

Fix #2291

discord/ext/commands/bot.py

@@ -729,7 +729,8 @@ class BotBase(GroupMixin):
             # if the load failed, the remnants should have been
             # cleaned from the load_extension function call
             # so let's load it from our old compiled library.
-            self._load_from_module_spec(lib, name)
+            lib.setup(self)
+            self.__extensions[name] = lib
 
             # revert sys.modules back to normal and raise back to caller
             sys.modules.update(modules)