Container not attached to network when hostconfig specified on start instead of create #19100
Description
We have a tool that interacts with the docker API directly and it started failing on master (aka 1.10, aka 723be0a). It tries to start containers with a custom network using the NetworkMode parameter in the start API. There is a warning that this will be removed in 1.12, but it looks like it already doesn't work for NetworkMode.
Example docker log when this fails:
DEBU[0061] Calling POST /v1.13/containers/create
DEBU[0061] POST /v1.13/containers/create?name=(redacted)
DEBU[0061] form data: {"AttachStderr":false,"AttachStdin":false,"AttachStdout":false,"Env":["NO_PROXY=(redacted)","HTTPS_PROXY=","HTTP_PROXY="],"Image":"(redacted):(redacted)","Memory":0,"MemorySwap":0,"NetworkDisabled":false,"OpenStdin":false,"StdinOnce":false,"Tty":false}
DEBU[0061] container mounted via layerStore: /var/lib/docker/overlay/a231abd7438a8a6dc86f68fe0e7abba14a63f89a00aa8076f3b88a0f23c2bb90/merged
DEBU[0061] Incrementing volume reference: driver local, name cc80f3f57a0a9b57e3d787c5062f37497732f0cc2da1874c031fc3290bb85e3c
DEBU[0061] Calling GET /v1.13/containers/json
DEBU[0061] GET /v1.13/containers/json?all=1&limit=-1&trunc_cmd=1&size=0
DEBU[0061] Calling GET /v1.13/containers/json
DEBU[0061] GET /v1.13/containers/json?all=0&limit=-1&trunc_cmd=1&size=0
DEBU[0061] Calling POST /v1.13/containers/(redacted)/start
DEBU[0061] POST /v1.13/containers/(redacted)/start
DEBU[0061] form data: {"Binds":["/var/(redacted):/var/(redacted):rw"],"NetworkMode":"(redacted)","PortBindings":{},"RestartPolicy":{"MaximumRetryCount":0,"Name":"always"},"SecurityOpt":["label:type:(redacted)"]}
WARN[0061] DEPRECATED: Setting host configuration options when the container starts is deprecated and will be removed in Docker 1.12
DEBU[0061] Decrementing volume reference: driver local, name cc80f3f57a0a9b57e3d787c5062f37497732f0cc2da1874c031fc3290bb85e3c
DEBU[0061] container mounted via layerStore: /var/lib/docker/overlay/a231abd7438a8a6dc86f68fe0e7abba14a63f89a00aa8076f3b88a0f23c2bb90/merged
DEBU[0061] Assigning addresses for endpoint (redacted)'s interface on network bridge
DEBU[0061] RequestAddress(LocalDefault/172.17.0.0/16, <nil>, map[])
Expected result: Container starts attached to the custom network
Actual result: Container starts on the default "bridge" network
