Backfill the changes required to skip the test_gsutil tests for gsutil.par tests. (#1481)
Backfill the changes required to skip the test_gsutil tests for gsutil.par tests. (#1481)

* Fix tests failing with gsutil.par

* assert_not_called does not work for python 3.5

* Rename variable
GoogleCloudPlatform/gsutil,GoogleCloudPlatform/gsutil