[tex-live] bug in TeX ?

[Taco Hoekwater]

Elie Roux wrote:
> Hello,
> 
> It looks like I have found a bug in TeX : here are the files : 
> http://norgz.info/bug.zip
> 
> The two files gregorio-good.tex and gregorio-bad.tex differ only in one 
> \showthe, and yet the result is different...
> 
> If it is not a bug can you explain my mistake, 

This:

   \global\isonaline=\number 0\iftrue1\fi

assigns 1 because the \if... is still part of the assignment.

Removing the % at the end of line 172

   \global\isonaline=\number 0%

fixes the wrong output.

Best wishes,
Taco