handle mercurial in-repository branches

[warner]

At the moment, our source.Mercurial step only handles darcs-style branches (where you have a bunch of repositories next to each other, one per branch, and you concatenate baseURL and the branch name to get the checkout).

Mercurial also has a feature where you can put multiple branches inside a single repository (using the 'hg branch' and 'hg branches' commands), in which certain revisions are marked as belonging to certain branches, and updating to a branch just means to get the latest revision that is marked that way. There are docs on this feature here:  http://hgbook.red-bean.com/hgbookch8.html#x12-1630008.5

We don't currently handle the latter kind of branch. source.Mercurial should acquire a 'inRepositoryBranch' flag or something. Either you give source.Mercurial a repourl and this flag=True, or you give it a baseURL+defaultBranch and this flag=False.

We also need to find out what version of mercurial acquired this feature, because I don't think it was there when I first looked at it.

[warner]

no progress on this yet, bumping to 0.7.8

[dsallings]

I have fixes for a few places where this is need in #185 #186 and #187

The first checkin I can find that added the user interface for these is October 2006. That should've made it into the 0.9.2 release.

[dustin]

Marcus says this is done - yay!

[marcusl]

Yup. I'll do some testing at our place on the 0.7.10 release candidate once it's ready. (hint hint) ;)