Ignore builds once they have been canceled

This change causes the gearman launcher to completely ignore builds
after the stop job request has been sent.  This should prevent
them from updating build status with confusing results.  It will
also help us avoid restarting canceled builds in a subsequent
change.

Change-Id: Id31bcbfb6f24a7ec9f5f0a776d7d2c30f36685b4
3 files changed