Handle additional reqs push failure as non failing

When pushing changes to gerrit for requirements proposals there are
cases where we want to ignore push errors. Specifically when gerrit is
complaining because you are pushing the same commit or one with
identical comments. We should just ignore these errors as it means the
current reqs proposal is up to date.

See
https://review.openstack.org/Documentation/error-no-changes-made.html
for more info.

Change-Id: I5d7a1991449a80f570191eaad49dc3f9a0ff1a6a
Merge "Handle additional reqs push failure as non failing"