ci: layer the python docker image on top of run-task

taskcluster/docker/python/Dockerfile

@@ -2,36 +2,17 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-FROM debian:bookworm-slim
+FROM $DOCKER_IMAGE_PARENT
 LABEL maintainer="Release Engineering <[email protected]>"
 
 VOLUME /builds/worker/checkouts
 VOLUME /builds/worker/.task-cache/uv
 
-# Add worker user
-RUN mkdir -p /builds && \
-    useradd -d /builds/worker -s /bin/bash -m worker && \
-    mkdir /builds/worker/artifacts && \
-    chown -R worker:worker /builds/worker
-
-# %include-run-task
-
 RUN apt-get update \
- && apt-get install -y --reinstall ca-certificates \
  && apt-get install -y --force-yes --no-install-recommends \
-    build-essential \
-    mercurial \
-    git
+    build-essential
 
+ENV PATH=/builds/worker/.local/bin:$PATH
 
-ENV SHELL=/bin/bash \
-    HOME=/builds/worker \
-    PATH=/builds/worker/.local/bin:$PATH
-
-# %ARG UV_VERSION
-COPY --from=ghcr.io/astral-sh/uv:$UV_VERSION /uv /bin/uv
 # %ARG PYTHON_VERSIONS
 RUN uv python install $PYTHON_VERSIONS
-
-# Set a default command useful for debugging
-CMD ["/bin/bash", "--login"]

taskcluster/kinds/docker-image/kind.yml

@@ -28,9 +28,9 @@ tasks:
         symbol: I(idx)
     python:
         symbol: I(py)
+        parent: run-task
         args:
             PYTHON_VERSIONS: "3.14t 3.14 3.13 3.12 3.11 3.10 3.9"
-            UV_VERSION: *uv_version
     run-task:
         symbol: I(rt)
         args: