If you upload two changes like:
    master HEAD -> A -> B
  and submit (or CQ) change A, which in the process gets rebased
  Then, you can't submit (or CQ) change B, because it depends on stale patchset of A.
     (most of discussion so far focused on whether it's a bug or a feature)
  Workaround: click "rebase" in B's UI before clicking "submit" (or CQ). Prior tryjobs will be re-used by CQ, so you won't need to wait longer.


The Gerrit issue is tracked here:  http://crbug.com/gerrit/5130 

This issue is to implement temporary workaround in CQ.