requiredContentMap does not exclude dead repos. Usually this is not a
problem because it is used when we are operating on a repository, and in
that case, the repository is not dead (or if it is, the required content
configurations should still be used). But in the case of fsck, this made a
old required content config for a dead repository be warned about in a
situation where it is not a problem.
updatecluster, updateproxy: When a remote that has no annex-uuid is
configured as annex-cluster-node, warn and avoid writing bad data to the
git-annex branch.
The proxy.log and cluster.log end up unparseable when a NoUUID gets written
to them.
If an input file has been lost from all repositories, it is no longer
possible to compute the output. This will avoid dropping content that
was computed in such a situation, as well as making git-annex fsck --from
the compute remote do its usual thing when content has gone missing.
This implementation avoids recursing forever if there is a cycle,
which should not be possible anyway.
Note the use of RemoteStateHandle as a constructor here suggests that
this may not handle sameas remotes right, since usually a
RemoteStateHandle is constructed using the sameas uuid for a sameas
remote. That assumes a compute remote can even have or be a sameas remote.
Which doesn't seem to make sense, so I have not thought through what might
happen here in detail.
