Partially revert 3603bae63c13 (issue23326) for asyncio.

Lib/asyncio/events.py

@@ -178,6 +178,10 @@ class TimerHandle(Handle):
                     self._cancelled == other._cancelled)
         return NotImplemented
 
+    def __ne__(self, other):
+        equal = self.__eq__(other)
+        return NotImplemented if equal is NotImplemented else not equal
+
     def cancel(self):
         if not self._cancelled:
             self._loop._timer_handle_cancelled(self)