The manifests we support marshalling/unmarshalling in composer are a
subset of the ones supported by osbuild. osbuild needs to preserve
backwards compatibility, but composer only needs to be concerned with
producing valid manifests at a given time.
A problem with this is that when we marshal our manifests to disk, and
read them out with a future version of composer, we would have to make
sure that the serialization is compatible, or unmarshalling the entire
store will fail. This is what happened when commit 5938276d3b
changed the way we marshal the file source.
Improve on this by only dropping those composes from the store on
unmarshal, whose manifests we are no longer able to unmarshal.
In future commits we will drop that requirement too.
Signed-off-by: Tom Gundersen <teg@jklm.no>
d606c5195b