Make r+ remove try bit

[Manishearth]

try followed by r+ doesn't work without a try- otherwise

r? @barosl

[barosl]

Hmm, the logic behind the current try handling is currently very confusing, and may require refactoring. But, AFAICT, try followed by r+ should work when the PR hits the top of the queue, because the try flag will be cleared at that time. Am I missing something?

[Manishearth]

I think that misses the case where new commits have been pushed since then.