MainClass.get_repo() used to default to lazy fetching, which is not what
NamedUser.get_repo() does, so change the default. Fix the tess to pass
lazy=True, so that we don't need to grow 8 ReplayData files with 11
lines of the repository in question.
Fixes#353
This field is not currently listed in the Github documentation at
https://developer.github.com/v3/pulls/reviews/, but it's been included
since Github 2.9
(It even exists in the test data returned for the original
PullRequestReview PR)
Steve Kowalik