Bug found in nightbuilds

[Torbjorn Granlund]

We currently have many spurious failures flagged in red at
<https://gmplib.org/devel/tm-date.html>, mainly due to hardware errors
with the  system `biko'.

But the `hark' failure looks real:

hark$  cd /var/tmp/gmp-obj/hark-stat-64
hark$  GMP_CHECK_RANDOMIZE=3526906869 tests/mpn/t-div
/home/tege/prec/gmp-snap/tests/mpn/t-div.c:486: GNU MP assertion failed: qp[nn-1] == qran1

This is an emulated machine, I can reproduce this also on real hardware.

I suspect this is a new bug, and that the error is in the test code.  It
seems to happen for many seeds, around one in 25, for s390.  If the bug
were old it'd had happened before.

Please let this list know if you want to work on this bug.  The hark
system is available to those with account at gmplib.org.

Torbjörn
Please encrypt, key id 0xC8601622