Switch back to correct (implicit) mediagoblin uid?

Dockerfile

@@ -47,7 +47,7 @@ RUN install_packages \
 
 COPY --from=build /usr/local/lib/python3.5 /usr/local/lib/python3.5
 COPY --from=build /usr/local/bin /usr/local/bin
-COPY --from=build --chown=1000:www-data /app /app
+COPY --from=build --chown=999:www-data /app /app
 COPY --from=build /sbin/tini /sbin/tini
 COPY mediagoblin_local.ini.template /app/mediagoblin_local.ini.template
 COPY uwsgi.yaml /etc/uwsgi/apps-enabled/mediagoblin.yaml
@@ -56,7 +56,7 @@ COPY wait-for /sbin/wait-for
 COPY run.sh /sbin/run.sh
 
 RUN addgroup --system mediagoblin \
-    && useradd --system --uid 1000 --gid mediagoblin --groups www-data --home-dir /var/lib/mediagoblin \
+    && useradd --system --uid 999 --gid mediagoblin --groups www-data --home-dir /var/lib/mediagoblin \
        --shell /bin/bash mediagoblin \
     && mkdir /app/user_dev \
     && chmod --recursive 0750 /app/user_dev \