Merge commit '1016795b404ffa0d12a817e68725268f70fb756e'
Allow zsh to source z.sh more than once.
Add support for zsh <=4.3.10.
chmod -x z.sh
Null merge remote-tracking branch 'upstream/master'

This fork uses a better way to determine the current shell.
Merge branch 'master' of git://github.com/knu/z