Gentoo's Bugzilla –
Attachment 512556 Details for
Bug 642972dev-python/jaraco-itertools-2.0 : [TEST] _pytest.vendored_packages.pluggy.PluginValidationError: Plugin case could not be loaded: (mock 1.3.0 (/usr/lib64/python2.7/site-packages), Requirement.parse( mock>=2.0 ))!