prepare-commit-hook now uses `git symbolic-ref HEAD` instead of reading
$GIT_DIR/HEAD directly. This seems to be a more portable solution.
Thanks to Chris (cs278/ToonArmy) for the suggestion.
Git supports several hooks, some of which are client-side. The
prepare-commit-msg hook is run right after a `git commit` call, before
the editor is opened. This allows the initial message to be altered.
This hook will check if the current branch name begins with `bug/`, in
which case it will prepend `[$branchname]` to the commit message. This
makes it easier to create proper commit messages.
http://wiki.phpbb.com/Git#Commit_Messages
For more information refer to the hook source.
