use __contains__, index or split instead of str.find str.find return -1 when the substring is not found, -1 evaluate to True and is a valid index, which can lead to bugs. Using alternatives when possible makes the code clearer and less prone to bugs. (and __contains__ is faster in microbenchmarks)

#!/bin/sh
hg init 1
echo '[ui]' >> 1/.hg/hgrc
echo 'timeout = 10' >> 1/.hg/hgrc
echo foo > 1/foo
hg --cwd 1 ci -A -m foo
hg clone 1 2
hg clone 2 3
echo '[hooks]' >> 2/.hg/hgrc
echo 'changegroup.push = hg push -qf ../1' >> 2/.hg/hgrc
echo bar >> 3/foo
hg --cwd 3 ci -m bar
hg --cwd 3 push ../2