reverse sense of return value from python hooks. old scheme (False/None/0/'' == fail) made coding style unnatural, did not allow use of mercurial commands as hooks. new scheme (False/None/0 == pass) is pythonic, does not require peculiar "return True" at ends of hooks, allows hooks like this: [hooks] # update working dir after push into this repo changegroup.update = python:mercurial.commands.update

Is there an error message when trying to diff non-existing files?
found: No such file or directory
not: No such file or directory
Is there an error message when trying to add non-existing files?
found: No such file or directory
not: No such file or directory