Duplicate rescue kernels

[supakeen]

Due to the way we handle /etc/machine-id in our images any image that has dracut-config-rescue will generate rescue kernel by the name of vmlinuz-0-rescue-ffffffff[repeat] (and initramfs) in XBOOTLDR.

When the system boots a new machine id is provisioned, the next time kernel-install runs and triggers dracut a new rescue kernel will be generated with vmlinuz-0-rescue-anactualidhere (and initramfs).

Since these together fill up about 150-200 MiB and 300-400 MiB when duplicated this can and sometimes does cause trouble for systems that try to keep 3 kernels and have a 1 GiB /boot partition.

[supakeen]

We have turned this off for Fedora Minimal now in #1245. However the issue remains for other images that if dracut-config-rescue is in their package set the above applies.

Looking at other build tools shows that they generally exclude the package on anything that's a disk image (installers tend to handle this case).

It's probably worthwhile to actually chase this rabbit down into Fedora by dropping the machine id from the BLS config(s) and kernel name(s). This can be done by fiddling with entry-token so let's test that and then maybe we can suggest it to distros.