`git annex sync --content` does not drop local unwanted content that
has been transferred to an exporttree remote.

This normally doesn't matter since exporttree remotes are untrusted, but
S3 with versioning enabled is not untrusted and once a file reaches such a
remote it should be able to be dropped locally. --[[Joey]]

Actually, there are two bugs here, because sync --content also fails to
drop local unwanted content that's got only 1 copy on another remote.
It forgot to include the local copy as a currently present copy, throwing
off the numcopies counting. --[[Joey]]

Both [[fixed|done]] --[[Joey]]
