Merge branch 'stable-2.6' into stable-2.7

* stable-2.6:
  Catch missing LDAP accounts in group membership
  Update patch status before skipping duplicate emails

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

Change-Id: If7173d50f09fa799e1cdd02e68b88aab00f1a1d9