Issue #20804: The unittest.mock.sentinel attributes now preserve their

identity when they are copied or pickled.

Lib/unittest/mock.py

@@ -238,6 +238,9 @@ def __init__(self, name):
     def __repr__(self):
         return 'sentinel.%s' % self.name
 
+    def __reduce__(self):
+        return 'sentinel.%s' % self.name
+
 
 class _Sentinel(object):
     """Access attributes to return a named object, usable as a sentinel."""
@@ -250,6 +253,9 @@ def __getattr__(self, name):
             raise AttributeError
         return self._sentinels.setdefault(name, _SentinelObject(name))
 
+    def __reduce__(self):
+        return 'sentinel'
+
 
 sentinel = _Sentinel()