Catch SIGHUP
This should reduce the chance that a repo we're connected to via ssh
gets interrupted without doing rollback.
+ hg init
+ echo '[hooks]'
+ echo 'precommit = echo precommit hook'
+ echo 'commit = echo commit hook: $NODE'
+ echo a
+ hg add a
+ hg commit -t test -u test -d '0 0'
precommit hook
commit hook: acb14030fe0a21b60322c440ad2d20cf7685a376