When I run the following code on Windows/Linux for < Python 3.6, I have no problems.  When I run in Python 3.6.0, I get the subsequent traceback.

I checked the release notes and only saw the following struct module note related to half-floats: Issue #11734

from struct import Struct
import copy
this_fails = Struct('<i')
copy.deepcopy(this_fails)


Traceback (most recent call last):
  File "test_script.py", line 12, in <module>
    copy.deepcopy(this_fails)
  File "F:\Anaconda\envs\py36\lib\copy.py", line 169, in deepcopy
    rv = reductor(4)
TypeError: can't pickle Struct objects


To be clear, I'm copying struct objects as part of a larger class.  As I'm running many function calls where I create the same struct objects, saving the common struct objects allows me to get a factor of 2x speedup on my code.  Deleting the saved struct objects at the end of file reading (and before the deepcopy takes place) fixes the problem.