8087e8d610
Python coverage lower than 3.6 causes issues when running the whole
test suite. Some arguments are randomly mixed up with script names,
resulting in unittest failures like this:
UnexpectedMethodCallError: Unexpected method call. unexpected:- expected:+
- exists.__call__('/tmp/buildd/.../nova/virt/images.py') -> None
+ exists.__call__('/some/path') -> True
Change-Id: Iadb6d046e3acc75c6ed5abffcfc1abda82aeee4f