It very well may apply to versions apart from 3.5. Our test environment is quite complex and unfriendly to working with multiple versions of Python. Plus, we're strapped for time, so we tend to file under the version we're currently targeting and defer to those better equipped and more familiar with the codebase.

The repro file is fine and there's no need to rebuild anything; the heap verification I'm suggesting is applied to binaries, not source. You can find information here:

https://msdn.microsoft.com/en-us/library/windows/hardware/ff549557(v=vs.85).aspx

Install the debugging tools, run GFlags, select the python.exe/pythonw.exe image file, and apply the settings I mentioned in my previous post.