run_rc_command succeeds if command not executable

[Edgar Fuß]

I wondered why mdnsd didn't start on boot without any trace in rc.log.

Now I found out it's /usr missing in critical_filesystems_local, but why 
on earth does run_rc_command() do
        if [ ! -x ${_chroot}${command} ]; then
                return 0
        fi
so this is silently ignored?