Somehow, copy() of a classic class object was handled
atomically, but deepcopy() didn't support this at all.
I don't see any reason for this, so I'm adding ClassType
to the set of types that are deep-copied atomically.
diff --git a/Lib/copy.py b/Lib/copy.py
index c1c0ec0..b57fa89 100644
--- a/Lib/copy.py
+++ b/Lib/copy.py
@@ -220,6 +220,7 @@
     pass
 d[types.TypeType] = _deepcopy_atomic
 d[types.XRangeType] = _deepcopy_atomic
+d[types.ClassType] = _deepcopy_atomic
 
 def _deepcopy_list(x, memo):
     y = []