test_from_array_with_subdomain_sizing segfaults on s390x

[mwhudson]

Full log here: https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-groovy/groovy/s390x/p/pygalmesh/20200908_152349_ba2b5@/log.gz

Running it by hand shows that this is the only test that crashes, the others all pass.

The traceback in gdb is this: https://paste.ubuntu.com/p/c3BS5wdN2r/ which I don't find very helpful. Happy to help debug this but don't really know where to start.

[nschloe]

Probably similar to #48. If I cannot reproduce the issue, there's nothing I can do right now.