Because tasks may be deleted while listing containers, we need to ignore
errors from state requests that are due to a closed error. All of these
get mapped to ErrNotFound, which can be used to filter the entries.
There may be a better fix that does a better job of keeping track of the
intended state of a backend task. The current condition of assuming that
a closed client is a shutdown task may be too naive.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
c80ca4f4a2