If we attach to a running container and stream is closed afterwards, we
can never be sure if the container is stopped or detached. Adding a new
type of `detach` event can explicitly notify client that container is
detached, so client will know that there's no need to wait for its exit
code and it can move forward to next step now.
Signed-off-by: Zhang Wei <zhangwei555@huawei.com>
Upstream-commit: 83ad006d4724929ccbde4bdf768374fad0eeab44
Component: engine