Starting with v4.5.0, if a token is found to be cached, but is cached
with an invalid state, the middleware attempts to log a debug message
indicating as much.
However, the logger it attempts to use does not exist and results in
an AttributeError. As a result, this yields HTTP 500 responses once
the invalid token gets cached and is attempted to be used again,
rather than the expected 401.
This fixes the reference and adds a test to ensure the expected log
entry ends up in the logger so that this condition in
AuthProtocol.fetch_token now gets coverage.
Change-Id: Ie391973ea5893531c0b590ffba2d9de7f7f19d94
Closes-bug: #1584289
f55b0334b9