SIGABRT with "Duplicate large block deallocation"

I have a crash (SIGABRT) "Duplicate large block deallocation" with the following three-lines code :

(ext:set-limit 'ext:heap-size 0) (setq a (expt 10 (expt 10 5))) (setq b (expt a 600))

Those lines come from sagemath's test suite... where they actually work!

I only get the problem with either the debian package of ecl, or by directly compiling the sources from sourceforge (version 13.5.1 in every case).

Daniel Kochmański confirmed on the ml that 15.2.21 also had the problem.