glacier-cli currently relies on a local cache of
inventory information, and so other git-annexes using the same glacier
repository are not able to access stuff in it, unless and until
`glacier vault sync` is run.

An example of this causing trouble is with the assistant. When a file is
moved into archive/, the assistant that sends it to glacier is able to
trust that it's in glacier and remove the local copy. But other assistants
that also have a copy cannot trust that, and so don't remove their copies.

I've discussed with glacier-cli's author making git-annex store enough info
in its branch to be able to bootstrap glacier-cli to know about a file.
This seems doable and he had a design; waiting on movement 
on the glacier-cli side.
