This really is weird. And I still can't reproduce it at all.

In the worst case, you can try disabling the spam.txt checker by commenting out the lines starting from:

my $spam_checker=compile_spam_checker(@spam_files);

in wakautils.pl until the end of the function.

I'll try to take a wild guess at what might be the problem and try to work around that a bit later, and give you some code to try instead, if you want.