### Check existing issues - [x] I've verified that this bug isn't described by any existing issues. ### Bug description When using the LXD provider (default provider), either the mmdebstrap plugin or the mmdebstrap command in an override-build command can fail with an error about `mknod`. This happens because, depending on the host's particular LXD configuration, the containers may allow the `mknod` call that mmdebstrap uses for testing while still failing the `mknod` call it uses to create `/dev/ptmx` in the chroot. When this happens, Imagecraft needs to be configured to fail on any `mknod` call in the container at all. ### Steps to reproduce 1. Get an imagecraft.yaml that uses mmdebstrap 2. Run it with the LXD provider ### Environment LXD configuration that allows a major, minor character device type of 1,2 but not of 5,3 ### imagecraft.yaml ```yaml ``` ### Log output ```shell ```