[infra] gen_task: follow-ups from http://review.skia.org/275076

Change-Id: I766c7e46f6f6da85411d1c4c65122c33e27a630d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/276197
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
3 files changed