pullrequests: don't show empty "additional changesets" (issue #280) When opening a pullrequest on a revision range including the tipmost revision, and then pushing a new revision on top of that, the PR page shows: This pullrequest can be updated with changes on ...: and then nothing. This is because the available revisions looped over are in 'avail_cs' but the guard around the loop is checking on 'avail_revs'. The former, while derived from avail_revs, can become empty under circumstances like this one. Fix the problem by changing the guard checking avail_cs rather than avail_revs, and making sure the printed message is aligned to 'No additional changes found'.