The way this ends up being called with the raspberry pi 4 image builder
ends up not using the `-e` from the shebang.

In turn, the builds fails during cross-compilation. The wrong coreutils
ends up being used, but this is not made apparent.

The issue I faced is already fixed on master, but this ensures no one
ends up with a failed build "succeeding".

This will be helpful in the now too-long-lived image for the Raspberry
Pi 4. We'll be able to properly configure the partition to be useful.

This should have been done initially, as otherwise it gets awfully
awkward to boot into new generations by default.

This system-specific image wasn't expected to be long-lived, thus why it
didn't end up being polished much.

Reality shows us we may be stuck with it for a bit longer, so let's make
it easier to use for new users.

Fix some pitfalls from the Raspberry Pi 4 specific sd image