[XeTeX] handling malformed UTF-8 input

[Sven Siegmund]

> ... A quick examination revealed that the source of the problem is the following comment, which makes XeTeX not see the following line with \fi-s:
>
>     \else\ifnum#1<\previous at toc@level
>         \addpenalty\@secpenalty % czy to dobra wartość?
>      \fi\fi

That is unbelievable. It would take me much longer that a 'quick
examination' to think about such a bug. It is amazing what unexpected
and hidden problems cause our non-ascii-characters, even today.

S.