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
#!/bin/sh
mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg undo
hg verify
hg parents
hg status