Merge 3.6 (fix #29519)

Lib/weakref.py

@@ -106,7 +106,7 @@ class WeakValueDictionary(collections.MutableMapping):
         self, *args = args
         if len(args) > 1:
             raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        def remove(wr, selfref=ref(self)):
+        def remove(wr, selfref=ref(self), _atomic_removal=_remove_dead_weakref):
             self = selfref()
             if self is not None:
                 if self._iterating:
@@ -114,7 +114,7 @@ class WeakValueDictionary(collections.MutableMapping):
                 else:
                     # Atomic removal is necessary since this function
                     # can be called asynchronously by the GC
-                    _remove_dead_weakref(d, wr.key)
+                    _atomic_removal(d, wr.key)
         self._remove = remove
         # A list of keys to be removed
         self._pending_removals = []