# Objective
fix#9452
when multiple assets are queued to a preregistered loader, only one gets
unblocked when the real loader is registered.
## Solution
i thought async_channel receivers worked like broadcast channels, but in
fact the notification is only received by a single receiver, so only a
single waiting asset is unblocked. close the sender instead so that all
blocked receivers are unblocked.
8a8d43d224