Opendiff as git merge tool on OS X

# I put these in my ~/.zshrc, you can put them in your .git/config if you prefer (but in a different format)
git config --global merge.tool opendiff
git config --global merge.opendiff.cmd ~/git-diff-cmd.sh
git config --global mergetool.prompt false

--- My ~/git-diff-cmd.sh (make sure you "chmod +x" it!) ---
#!/bin/sh
/usr/bin/opendiff "$2" "$5" -merge "$1"

--- How to use it ---
$> git rebase master
[...]
CONFLICT
$> git mergetool
[opendiff opens]