From time to time, unit tests execution fails with error: "TypeError:
'NoneType' object is not iterable". It seems that problem is in
unittest2 library, which is used by testtools for executing the tests.
Stestr lib is usinig unittest by default and the problem does not appear
for several hundred launches.
Authored-By: danpawlik <email@example.com>
Signed-off-by: Gael Chamoulaud (Strider) <firstname.lastname@example.org>
Python 3.8 is now our highest level supported python runtime.
This updates the default tox target environments to swap out
py37 for py38 to make sure local development testing is
covering this version.
This does not impact zuul jobs in any way, nor prevent local
tests against py37. It just changes the default if none is
Signed-off-by: Sean McGinnis <email@example.com>