Merge branch 'stable-2.6'

* stable-2.6:
  Enable expanding skipped lines even if 'Syntax Coloring' is off
  Fix: `gerrit review` with --message does not work with no labels
  Reword 'Working ...' message changes in 2.6 release notes
  TrivialRebase: Support custom labels
  MergeUtil: Remove legacy label ID
  TrivialRebase: Call gerrit review instead of approve