[BUG] Dockerfile's ONBUILD command fails at --chown=evennia

[poisonbl]

Describe the bug

Dockerfile's ONBUILD command fails at --chown=evennia because the user hasn't been created.

To Reproduce

Create a Dockerfile consisting of:

FROM evennia/evennia:latest

ENTRYPOINT evennia start -l

Run docker build . in the folder with it.

$ docker build .
DEPRECATED: The legacy builder is deprecated and will be removed in a future release.
            Install the buildx component to build images with BuildKit:
            https://docs.docker.com/go/buildx/

<download spam>
Sending build context to Docker daemon  5.153MB
Step 1/2 : FROM evennia/evennia:latest
# Executing 1 build trigger
unable to convert uid/gid chown string to host mapping: can't find uid for user evennia: no such user: evennia

Expected behavior

The evennia image build should either preemptively create the user, or not incorrectly expect it to be their for a derivative build.

Additional context

Appears to've been introduced potentially as far back as Dec 2, 2022 in 86e2722

Simplest fix would likely be just to change

ONBUILD COPY --chown=evennia . /usr/src/game

to

ONBUILD COPY . /usr/src/game