Forgot to update script after updating the post.

content/static/runas

@@ -3,4 +3,6 @@ set -eu
 command -v sudo > /dev/null || { echo "Can't find sudo, exiting."; exit 1; }
 uid="$(stat . --format '%u')"
 gid="$(stat . --format '%g')"
+groupadd --force --non-unique --gid "$gid" builder
+useradd --non-unique --gid "$gid" --home-dir /volume --no-create-home --shell /bin/sh builder
 sudo -Eu "#$uid" -g "#$gid" -- "$@"