Inconsistent copy.deepcopy across Python 2.7 / 3.5 versions

deepcopy_threading_local.py

"""
Python 3.5.2 (default, Dec 17 2016, 20:19:49)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.38)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import threading
>>> import copy
>>> x = threading.local()
>>> x.a = 1
>>> y = copy.deepcopy(x)
>>> y.a
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: '_thread._local' object has no attribute 'a'


Python 2.7.13 (default, Dec 17 2016, 20:15:44)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.38)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import threading
>>> import copy
>>> x = threading.local()
>>> x.a = 1
>>> y = copy.deepcopy(x)
>>> y.a
1
>>>
"""