Finally - thanks to btkaos's script - here attached you find a full backtrace with downloadlimit set to 0 on a linux machine.
Hi ^marcell^, the backtrace looks similar to some of the one I got, but it is not informative as it doesn't show the allocation path.
No symbol table info available.
Would you mind to use debug versions of the libraries (in Debian those are the -dbg stuff and --with-wxdebug in amule's config)
Maybe next time you should press "c" and "Ctrl-C" in gdb to get the backtrace of the allocation path.
The bug was not exclusive of donwloadlimit, that just made it more likely to happen. Have you tried the wx patch? Did it help?