VCS_INFO_realpath () { #{{{
    # a portable 'readlink -f'
    # forcing a subshell, to ensure chpwd() is not removed
    # from the calling shell (if VCS_INFO_realpath() is called
    # manually).
    (
        (( ${+functions[chpwd]} )) && unfunction chpwd
        setopt chaselinks
        cd $1 2>/dev/null && pwd
    )
}