use unittest.mock instead of mock

[pgajdos]

Could you please consider to utilize unittest.mock? It seems you support older pythons, so you probably cannot really remove mock usage, but unittest.mock could be used as a fallback.

Background:
https://trello.com/c/S6eADbii/64-remove-python-mock
https://fedoraproject.org/wiki/Changes/DeprecatePythonMock

[deltoura]

Or would you consider dropping support for Python 2.7? (which has officially reached its end of life anyway)

[bittner]

Or would you consider dropping support for Python 2.7? (which has officially reached its end of life anyway)

See #1030 for a related discussion.