grub and ostree disagree on BLS versioning

[cgwalters]

OK so I was playing around with alternative stateroots (i.e. ostree admin os-init backup; ostree admin deploy --os=backup $commit) and made an unfortunate discovery.

Today, ostree writes BLS files with a version entry in them, and that's what it thinks the bootloader order should be.

grub2 though seems to be parsing the filenames...as if they were RPM packages actually. See this code: https://github.com/rhboot/grub2/blob/7de33f4072abf5f14c4fdad6e566c58bdbf3b26e/grub-core/commands/blscfg.c#L400

And what's ugly here is what ostree writes into the filenames looks like ostree-$version-$stateroot. Except...that parsing code splits on -. So things go badly if the stateroot name contains -...as it does for fedora-coreos.

We end up with (I think)

name=ostree-$version
version=fedora
release=coreos

This isn't exactly problem if one only has one stateroot...we'll still correctly sort on the ordering of "name" here...it's just ugly.

However, it does completely break the ability to use alternative stateroots because then the parsing of things just breaks.

I think we could probably change the filenames we emit to match this schema. Hmm...probably we need the version to go first to reliably fix this, and then encode everything else into the version field or so?

[cgwalters]

I think last time I looked at this it looked like zipl at least did read the version field.