Fix an issue with clearing permission rules (#3015)

Fixes #3014

redbot/core/commands/commands.py

@@ -573,6 +573,14 @@ class Group(GroupMixin, Command, CogGroupMixin, commands.Group):
 class CogMixin(CogGroupMixin, CogCommandMixin):
     """Mixin class for a cog, intended for use with discord.py's cog class"""
 
+    @property
+    def all_commands(self) -> Dict[str, Command]:
+        """
+        This does not have identical behavior to 
+        Group.all_commands but should return what you expect
+        """
+        return {cmd.name: cmd for cmd in self.__cog_commands__}
+
     @property
     def help(self):
         doc = self.__doc__