Fix tests for Git submodule

[agjohnson]

I can't explain why this isn't happening for everyone, however the issue I git
was that my global git config wasn't being picked up. This explicitly sets the
user name and email to avoid erroring out on the following calls.

[davidfischer]

This wasn't necessary for me so there must be something with your setup. However, better to be explicit.

[humitos]

I didn't have this problem in my local setup either.

I remember that I had this problem when I was working with the VCS code and this was exactly the problem: wrong GIT_DIR environment variable.

This isn't dangerous as it is, but a small change will end up changing the global git defaults in the under the current user.

As David said, I suppose that it's better explicit here. So, we are good.

(I tested this locally by running all the py36 tests and did work)