run_rc_command succeeds if command not executable

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

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?