Add ref parameter when creating a try job

This fixes git cl try when revision is passed.

R=ehmaldonado@chromium.org

Bug: 1138785
Change-Id: Id5a067114426ed55409b1f200abf4d5a38fdbaa5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2691312
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
diff --git a/git_cl.py b/git_cl.py
index 6e7e148..c02d23e 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -392,10 +392,12 @@
     })
 
     if options.ensure_value('revision', None):
+      remote, remote_branch = changelist.GetRemoteBranch()
       requests[-1]['scheduleBuild']['gitilesCommit'] = {
           'host': gerrit_changes[0]['host'],
           'project': gerrit_changes[0]['project'],
-          'id': options.revision
+          'id': options.revision,
+          'ref': GetTargetRef(remote, remote_branch, None)
        }
 
   return requests