Comment 1 for bug 1670577

The rally job was working fine on May 1st, https://review.openstack.org/#/c/199387/, and the jobs that we run internally with rally stable branch are working.

This commit seems to affect the way that rally validates tasks
https://github.com/openstack/rally/commit/4dcb597949bebaaaad3f2eacdce2f6bb9b480cb3

anyway, we need to investigate more, but most likely is because of an incompatible change in rally.