Retry command is too picky

[reiddraper]

The code specifically matches on '@username: retry'. The colon shouldn't be necessary. And it should allow you to retry on the pull-request itself with a sha: '@username retry deadbeef'.

[parkr]

Not quite sure, but it looks like it's here:

bors/bors.py

Line 370 in a6b07e6

c.startswith("@"+self.user+": retry"))])

I'd go ahead and submit a PR with a regexp fix just looking for / retry [a-z0-9]{7,40}?/ but not sure if that's a good solution or not.