Updating notebooks using Git pull changes owner to root

If you use git pull to update the notebooks the changed files get the owner and group root:root. This makes the notebook unable to be saved. I tried correcting this locally(docker) by using the $chown --preserve[=ATTR_LIST] but that did not seem to work for some reason.

Start by inspecting the repository's Dockerfiles and the notebook update workflow, then reproduce a git pull inside the Docker environment. Trace why updated files become owned by root:root and determine the expected ownership that allows notebooks to be saved. Done means updates retain writable ownership for the notebook user.

索引モデルが issue の本文から書いたものです。