MIPSEL: SIGBUS in t-div (fmpq_mpoly)

[SnarkBoojum]

I could get the following trace with gdb:

Program received signal SIGBUS, Bus error.
0x77d70b28 in fmpz_mpoly_quasidivrem_heap (scale=<optimized out>, q=<optimized out>, r=<optimized out>, poly2=0x7fff4478, poly3=<optimized out>, ctx=<optimized out>) at quasidivrem_heap.c:868
868           exp2 = (ulong *) flint_malloc(N*poly2->length*sizeof(ulong));
(gdb) bt
#0  0x77d70b28 in fmpz_mpoly_quasidivrem_heap (scale=<optimized out>, q=<optimized out>, r=<optimized out>, poly2=0x7fff4478, poly3=<optimized out>, ctx=<optimized out>) at quasidivrem_heap.c:868
#1  0x77d81a98 in fmpq_mpoly_divrem (Q=0x7fff44a8, R=0x7fff44c4, A=0x7fff4470, B=0x7fff448c, ctx=0x7fff4500) at divrem.c:35
#2  0x55552918 in main () at test/t-div.c:348