bad error message when building bootc-installer from an unavailable image

```
$ sudo ./image-builder build --bootc-ref asd bootc-installer
WARNING: bootc support is experimental
[/] Manifest generation step
Message: Building manifest for bootc-based-bootc-installer
error: running asd container failed: exit status 125
stderr:
Error: short-name resolution enforced but cannot prompt without a TTY
```

If I didn't know what was happening, I would be puzzled. :)