I found out that if one of the labels in bar-chart exceed a certain length (11 bytes), this kind of crash occurs. When looking at the source code of the Debian distribution, the reason is obvious:
slen = PyString_Size(pstr); if ((slen = 0)) goto cleanup; mem = malloc((size_t)slen+1); And the change made at Debianization was: @@ -712,7 +713,7 @@ if (pstr == NULL) goto cleanup; slen = PyString_Size(pstr); - if (slen == NULL) + if ((slen = 0)) goto cleanup; mem = malloc((size_t)slen+1); if (mem == NULL){