The blind-idiot method of solving this problem would be to impose a timeout (probably 2x the specified one) on the client side. This is enough of an edge case that I think it's probably not worthwhile to find a more intelligent check.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/710731dfdf64180121e28e3fee89eb44a3d27618

commit 710731dfdf64180121e28e3fee89eb44a3d27618
Author: Jacob Kopczynski <jkop@google.com>
Date: Fri Dec 15 07:57:28 2017

container_pool: Remove client reliance on cxn

Client has a bare wait for a return from the server, relying on a
server-side guarantee that a return will be sent within the timeout.

This is not robust to problems with the connection, so this adds a
timeout on the client side. This changes it to a configurable
server-side timeout for a pool to be created, plus a client-side added
timeout for connection issues after which a return is presumed
impossible and will be ignored.

BUG= chromium:794026 
TEST=Added to client_unittest

Change-Id: I829fc9aa988773962ee1648c287de696a3454976
Reviewed-on: https://chromium-review.googlesource.com/823643
Commit-Ready: Jacob Kopczynski <jkop@chromium.org>
Tested-by: Jacob Kopczynski <jkop@chromium.org>
Reviewed-by: Ben Kwa <kenobi@chromium.org>

[modify] https://crrev.com/710731dfdf64180121e28e3fee89eb44a3d27618/site_utils/lxc/container_pool/client_unittest.py
[modify] https://crrev.com/710731dfdf64180121e28e3fee89eb44a3d27618/site_utils/lxc/container_pool/service.py
[modify] https://crrev.com/710731dfdf64180121e28e3fee89eb44a3d27618/site_utils/lxc/container_pool/client.py