231f3b4760
Until now no unit tests have been executed in py37 environment. This change fixes tox configuration to enable running these tests. It also fixes two unit tests to handle PEP479 being enabled for all code in Python 3.7 [1, 2]. [1] https://docs.python.org/3/whatsnew/3.7.html#changes-in-python-behavior [2] https://stackoverflow.com/questions/51700960/runtimeerror-generator-raised-stopiteration-every-time-i-try-to-run-app Change-Id: I7fcf30d848efb8dc4cc6ca19056868aa6127cf60