Note: the doc text is the same as for BZ 1275986, i don't think we want to release this text twice, so i'm setting requires_doc_text-.
Cause: Pacemaker prevented Puppet from restarting services during overcloud update.
Consequence: Puppet run failed, which caused overcloud update to fail.
Fix: Pacemaker is put into maintenance mode for the duration of Puppet run during the overcloud update.
Result: Puppet is allowed to restart services, and it doesn't cause the overcloud update to fail anymore.