[mc] Putting back usermod solution

minecraft-server/start.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+set -e
+usermod --uid $UID minecraft
+groupmod --gid $GID minecraft
+
+chown -R minecraft:minecraft /data /start-minecraft
+chmod -R g+wX /data /start-minecraft
+
+while lsof -- /start-minecraft; do
+  echo -n "."
+  sleep 1
+done
+echo "...switching to user 'minecraft'"
+exec sudo -E -u minecraft /start-minecraft