Add commit needed-by

In order to find reverse dependencies specified by cross-repo
"Depends-On" headers, search for the occurance of a given change-id
in commit messages, and then filter the result set for "Depends-On"
headers.

Add those cross-repo reverse dependencies to the already supplied
Gerrit git reverse dependencies.  This should cause behaviors
such as automatic enqueuing of reverse dependencies on merges to
apply to CRD as well as git-dependencies.

When collecting reverse CRD, update cached Zuul change records.
This corrects a bug where if change A depends on B in a different
repo, and change B is updated with a new patchset, Zuul's cached
record for change A will still point to the old patchset of change
B.  This change corrects that by causing B to trigger a refresh of
A when the reverse CRD is noted.

Change-Id: I1bcf1f0fa0ea1c20b01ea478a83f179b612a0ae9
4 files changed