hooks: add a prewlock and a prelock hooks This is useful for testing.

exchange: fix locking to actually be scoped The previous code was taking locks before entering with statements, so exception before the with statement would not release the lock (except for garbage collection). We need to move to a try except here because the logic is more complicated.

exchange: fix locking to actually be scoped The previous code was taking locks before entering with statements, so exception before the with statement would not release the lock (except for garbage collection).

narrow: add a test for linkrev computation done during widen This new tests show that the linkrev computed and sent by the server might end up being wrong during a widen operation.

obsolete: quote the feature name This makes it at least somewhat clearer that hg is talking about some specific feature and not just outdated code.

branching: merge stable into default