Docker cp - file ownership

Version 1.12.0-rc2-beta16 (build: 9493)

Running on a mac, previously using docker-machine, whenever a docker cp was issued to copy a file from the host to the container, the file would be owned by the proper user/group, ie. the same user you end up assuming when you issue a docker exec to connect to the shell, in our case the node user. So docker cp would copy the file to the container and it would have the user:group of node:node.

Under the latest beta, the files are being owned by root:root. This is causing an issue under our angular app due to file permissions. I even tried to set the user/group sticky bit on the directory to force any files within to be owned by the proper user, but that appears to be completely ignored and the file is still owned by root:root.

Is this expected behavior?