Previously, RBTools calculated outgoing Mercurial changesets by asking

Mercurial about *all* changesets on the current branch not in the

remote. While this works, it's not ideal. This querying is expensive

since it pulls in all changesets, not just ancestors of the eventual

changesets.
With this patch, we now pass "-r ." into hg outgoing. This limits the

lookup to changesets that are ancestors of the working copy. In some

repository configurations (such as my own, where I have bookmarks

tracking thousands of changesets that will never be pushed to the

remote), this drastically speeds up diff computation and makes RBTools

faster.