force-one-head

#!/bin/bash
# force-one-head
# add the following to <repository>/.hg/hgrc :
# [hooks]
# pretxnchangegroup.forceonehead = /path/to/force-one-head

if [ $(hg heads --template "{branch}\n"|sort|uniq|wc -l) != $(hg heads --template "{branch}\n"|sort|wc -l) ]; then
    echo "There are multiple heads."
    echo "Please 'hg pull' and get your repository up to date first."
    echo "Also, don't 'hg push --force' because that won't work either."
    exit 1
fi