Test failure in test-crypto-secret.c

When running qemu test suite I'm seeing a test failure:

ERROR:../qemu/tests/test-crypto-secret.c:144:test_secret_keyring_good: assertion failed: (key >= 0)

Host is Arch Linux running in the standard Arch build environment (essentially an nspawn container).

I first noticed this at release of 5.1.0 but it's still there on current trunk. For 5.1.0 I was able to sidestep the issue by building with `--disable-keyring' but this no longer works (I think due to 9866a33cbb7046891dec3dcc9ca2015828673afe)

Any clues on what might be the cause? Not sure how to debug.