f9f3b275099cfe7b38d535402c9a905166c2dc88

When a change is submitted but fails to merge, execute the `merge-failed` hook and send the `merge-failed` event to the event stream. Bug: Issue 1237 Change-Id: Iab988b3cfc29f22450a8f25148a53ea131e184a7
Description
RETIRED, Gerrit as used by OpenStack