Blocks the execution of tasks during the Prepare phase until there
exists an IP address for every overlay network in use by the task. This
prevents a task from starting before the NetworkAttachment containing
the IP address has been sent down to the node.
Includes a basic test for the correct use case.
Signed-off-by: Drew Erny <drew.erny@docker.com>
Upstream-commit: 3c81dc3103d9c88cb333c80e0810f80ab80c374e
Component: engine
e44dbe9123