autotest: Suppress bogus errors found by newer version of pylint

After reviewing the failures, we added a bunch of new
exceptions, so we continue to get clean pylint reports.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #897 from autotest/fix_pylint

autotest: Suppress bogus errors found by newer version of pylint