cbuildbot: a workround for adding ts_mon_task_num to old branches.

BUG=chromium:740562
TEST=None

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>
(cherry picked from commit fcedd74f8eaa92d2e4d8e190a07ac91d7e650222)
Reviewed-on: https://chromium-review.googlesource.com/573354
Reviewed-by: YH Lin <yueherngl@chromium.org>
Commit-Queue: YH Lin <yueherngl@chromium.org>
Tested-by: YH Lin <yueherngl@chromium.org>
(cherry picked from commit 8e5e637cad43268879d3f3b1d3ddce346be9e113)
Reviewed-on: https://chromium-review.googlesource.com/575067
1 file changed