Mercurial Queues - Mozilla Developer Center

"Mercurial Queues, or MQ, is a Mercurial extension that lets you keep work in progress as mutable patches, instead of as immutable changesets. ... The output of a developer (on a good day, anyway) is patches. The MQ extension lets you treat a stack of patches as works-in-progress. You can apply them as Mercurial changesets, unapply them, edit them, and when they're done, turn them into permanent changesets and push them."