Restrict /changes/{id}/revisions/{commit} one change

If the same commit SHA-1 is pushed to multiple changes
(e.g.  different projects) the /revisions/ collection
was failing to match by SHA-1 due to duplicate results.

The parent ChangeResource provides a way to filter to
more narrow result set, a revision is only valid if it
is known to the parent change.

Change-Id: I76607e31b38a373f0d23447f638ccb242a4083ac
1 file changed