Merge branch 'stable-2.9'

* stable-2.9:
  Prevent possible NPE in AuthorRevision.equals
  ChangeUpdate: fix comparison of Change.Id to Change.Key
  ChangeInserter: fix comparison of Change.Id to Change.Key

Conflicts:
	gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeInserter.java

Change-Id: I0d35ac1e6a0b6d00bceee3c0adc5bf98dcc43566