nbd-client --help causes Segmentation fault on 1:3.27.1-1 / latest git

Verified with a fresh build from git:

```shell
root@93695b5decca:/data/build# ./nbd-client --help
Segmentation fault         ./nbd-client --help
root@93695b5decca:/data/build# ./nbd-client --version
ERROR: no information specified

...
```