Description
Tags — we haven't got any tests with tags, and if there are any tags it will currently throw an UnsupportedOperationException. The implementation of tags should be basically the same as git's so it should be fairly straightforward.
Maybe be tricky to add support for tags on unmerged branches.
Hg tags are versioned, so we need to check if we're getting all tags when we call hg tags. Ideally, we would get all the tags even for unmerged branches, as they would probably be menaingful to people, but that may be next release.
Verify which version of the tags file we get.
