Homu stuck in 'try' state

[KiChjang]

When a try build fails (due to intermittents) and someone r+ it after the try failure, Homu seems to still be stuck in the 'try' state, i.e. it would display "trying commit ..." instead of "testing commit ..." when building the PR, and it would not merge the branch into master. servo/servo#10670 is an example of this behaviour.

EDIT: Using r+ clean does not seem to solve the problem.

[Manishearth]

You need to try- it. I had a PR somewhere that made r+ imply try-, but it wasn't accepted upstream.

This is fixed by #7