The goal is to make it more clear this will give you the container id after run completes.
Since stdout is now standard on run, "docker run -d" is the best (or only) way to get the container ID returned from docker after a plain run, but the description (help) does not hint any such thing.
Upstream-commit: 5dc86d7bca17c2996264a18cc26f06d30e532588
Component: engine