Comment # 4 on bug 1100690 from Thomas B. R�cker

OK, so this is really obscure. More random poking, stracing, guessing.

 export -n MALLOC_CHECK_

*bam* it builds inside the chroot and using `osc build`

conversely doing this on an openSUSE Leap 15:

 declare -x MALLOC_CHECK_="3"

makes it segfault!

So this looks like yet another malloc bug in makensis?
For my purposes I'm going to do the ugly workaround of unsetting MALLOC_CHECK_
and MALLOC_PERTURB_ right before calling `makensis` in my RPM spec.

I guess you might want to tell upstream about this.