Make flake8-bugbear happy

[kpinc]

flake8-bugbear declares:

B017 'assertRaises(Exception)' and 'pytest.raises(Exception)' should be considered evil.

This eliminates the complaint.

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Again, it is unclear what the best match re is, or the more specific exception trap is.

The last hunk (match="BadLoader") produces the exception:

<ExceptionInfo AttributeError("'BadLoader' object has no attribute 'setup_logging'") tblen=3>

The earlier 3 hunks produce exceptions that rep like (differing only in the scheme reported):

<ExceptionInfo LoaderNotFound('Could not find a matching loader for the scheme "file+bad".') tblen=4>

I believe that match re-s given are a good representation of the expected error,s but I did the obvious thing and didn't think too deeply.