PluginLoadError from mismatched requirements

[zroger]

Between 1.2.2 and 1.2.3 my test suite started raising this exception:

tavern.util.exceptions.PluginLoadError: Error loading plugin requests = 
tavern._plugins.rest.tavernhook:TavernRestPlugin - (PyYAML 5.3.1 (/var/task), Requirement.parse('PyYAML==5.3'))

I have an unpinned PyYAML requirement in my project which is how I ended up with version 5.3.1, but tavern 1.2.3 wants exactly version 5.3, which was pinned in #577. Digging through the code, it looks like the exception comes from stevedore because the verify_requirements argument is used when loading the plugins.

To get around this issue, I've pinned tavern to 1.2.2 rather than pinning PyYAML since 5.3.1 is a security fix.

I'm not sure how to proceed to fix this in the long run. The two options I can see are to give the PyYAML requirement a looser version specifier, or to remove the verify_requirements argument. If you let me know which you prefer, I can try to put together a patch.

[michaelboulton]

Should be fixed in 1.2.4