cbuildbot: a workround for adding ts_mon_task_num to old branches.


Change-Id: I3228856d0064dbf3bdfaf122d0d61f5ae0d18469
Reviewed-on: https://chromium-review.googlesource.com/565900
Commit-Queue: Xixuan Wu <xixuan@chromium.org>
Tested-by: Xixuan Wu <xixuan@chromium.org>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index cbc0e36..a965b74 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -705,6 +705,10 @@
                    help='Used for compatibility checks w/tryjobs running in '
                         'older chromite instances')
   group.add_option('--sourceroot', type='path', default=constants.SOURCE_ROOT)
+  group.add_option('--ts-mon-task-num', type='int', default=0,
+                   help='The task number of this process. Defaults to 0. '
+                        'This argument is useful for running multiple copies '
+                        'of cbuildbot without their metrics colliding.')
   group.add_remote_option('--test-bootstrap', action='store_true',
                           help='Causes cbuildbot to bootstrap itself twice, '