merge: make hg.merge() take a context instead of a node Many callers already have a repo, so we might as well pass that. `merge.update()` will look up the context object later. This patch is part of making it so we pass around the context object all the way down instead. I also removed the `repo` argument since it can be retrieved from the context. Differential Revision: https://phab.mercurial-scm.org/D7999