gerrit 2.7-rc4
Merge branch 'stable-2.6' into stable-2.7

* stable-2.6:
  Fix browser NPE when ChangeCache is incomplete

Conflicts:
	gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeDescriptionBlock.java
	gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/PublishCommentScreen.java

Change-Id: Ib1c1166426c65c5ae44cb2146bc4566b38c16cc4