Crashes can happen when freeing memory with an incorrect free memory function.
1- relay plugin is loaded
2- ssl relay is created, gnutls allocates memory with its default allocator
3- guile plugin is loaded, guile register its custom gmp allocators
5- relay plugin deinits gnutls -> gnutls deinits gmp -> gmp tries frees
memory. Some memory allocated with malloc is passed to custom_gmp_free which
is not correct => possible segfault
I've attached a simple patch to prevent guile from registering its gmp