Bug#991750: nauty: segfaults during sagemath testsuite

[Ahzo]

Package: nauty
Version: 2.7r1+ds-2
Severity: important
Control: affects -1 sagemath

Hi,

during the sagemath testsuite, a nauty crash occurs. Nonetheless, the sagemath test passes:
sage -t --long --random-seed=0 src/sage/graphs/digraph_generators.py
    [150 tests, 6.44 s]

The crash can be easily reproduced:
$ nauty-gentourng -d0 -D1 -c 2
>A nauty-gentourng -cd1D0 n=2
Segmentation fault (core dumped)

Anyway, nauty should not crash like this, particularly since the input seems valid.

Regards,
Ahzo