Even on small changes e.g. one file - git-review producing extensive description on PR

[kalabiyau]

• forked from master
• pushed PR with one commit
  PR description shows huge set of changes

@b4mboo know more about it that me, because i never took a proper look to git-review internals.

[b4mboo]

This seems to be a bug when merging master into the feature branch. The prefilled PR description lists all the commits, which can be a bit misleading if you only have a small change in one single commit and the PR's description shows 20 (or more) commits which are already on master.

[b4mboo]

So we need to adjust the way the description is generated and filter out commits that have already been merged to master.