Homu doesn't kick off tests anymore and does not merge anything

[Ms2ger]

CC @aneeshusa @Manishearth @larsbergstrom @metajack @edunham

Both in Servo and travis-backed repos:

• servo/euclid#156
• #12822

[jdm]

If the last Travis run was against the same revision as the requested merge, home has a shortcut mode that doesn't bother redoing the build. This is a good thing.

[Manishearth]

That's not what's happening here -- in that case it explicitly says "test exempted" and merges

[larsbergstrom]

Fixed! The problem is that the homu directory had permissions root:root but the service is supposed to run as the servo user. I cleaned things up manually, and @aneeshusa is going to work on a PR to ensure our salt rules set up things perfectly from a clean directory.