Issue: RC increases also when the block ref entry is first put by the actual client.
At that point the client is probably already sending us the block content,
so we don't need to do a get...
We should add a delay before the task is added or find something to do.
So the HTTP client future of Hyper is not Sync, thus the stream
that read blocks wasn't either. However Hyper's default Body type
requires a stream to be Sync for wrap_stream. Solution: reimplement
a custom HTTP body type.
