mount's "-n" switch is supposedly useful to tell it to not touch /etc/mtab. But well, it will still create it just not write anything to it. Hence, if you boot up with no /etc/mtab at all, and you invoke mount with "-n", then the file will exist in an invalid state after that...

(Also, it's probably time to just remove support for /etc/mtab, and just support symlinked setups. But anyway, that's a different story. For now all I want is that "-n" does what it is advertised for: not touch /etc/mtab at all, and that includes not creating it.)