Clean up both _func_cid_map and callbacks

Author: vallsv

lib/matplotlib/cbook/__init__.py

@@ -216,12 +216,11 @@ def _remove_proxy(self, proxy, *, _is_finalizing=sys.is_finalizing):
         if _is_finalizing():
             # Weakrefs can't be properly torn down at that point anymore.
             return
-        for signal, proxies in list(self._func_cid_map.items()):
-            try:
-                del self.callbacks[signal][proxies[proxy]]
+        for signal, proxy_to_cid in list(self._func_cid_map.items()):
+            cid = proxy_to_cid.pop(proxy, None)
+            if cid is not None:
+                del self.callbacks[signal][cid]
                 break
-            except KeyError:
-                pass
         else:
             # Not found
             return

lib/matplotlib/tests/test_cbook.py

@@ -261,7 +261,6 @@ def test_callback_wrong_disconnect(self):
         # check we still have callbacks registered
         self.is_not_empty()
 
-    @pytest.mark.xfail(reason="must be fixed")
     def test_registration_on_non_empty_registry(self):
         # ensure we start with an empty registry
         self.is_empty()