Fixes to trigger_wait_ac_task.py

Turns out I made the exact same mistake 2.5 years ago:
https://codereview.chromium.org/1373863002/

NoTry: true
Bug: skia:7469
Change-Id: Id21150db072f2e9cb8e4e4b8462cac1a085a5193
Reviewed-on: https://skia-review.googlesource.com/102481
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
1 file changed