lock: show more detail for new-style locks in lock waiting message (issue4752) Improve the lock waiting warning message by explicitly saying that a host and process are holding the lock. This nudges confused new users in the direction of investigating the other process instead of removing the lock.

formatter: add context manager interface for convenience And port "hg files" to test it. As you can see, extra indent is necessary to port to this API. I don't think we should switch every fm.formatter() call to "with" statement.

histedit: remove now unused 'constraints' related code Now that the one action that need different logic handle that using inheritance and overriding, we can remove that code.