implement fix for color mode default

entrypoint.sh

@@ -341,8 +341,10 @@ fi
 # Apply optional queue defaults from PRINTER_OPTIONS (see README). Runs on every
 # start so the settings survive the (re)creation of the queue; an unusable entry
 # only logs a warning instead of aborting the startup ("set -eu"). Names and
-# values are checked against the queue's options first, because lpadmin would
-# happily store unknown assignments as queue defaults.
+# values are checked against the queue's options first: lpadmin accepts unknown
+# assignments with exit status 0 and silently drops them, so without the check a
+# typo would look like a successfully applied default while the printer keeps
+# using the PPD default.
 apply_printer_options() {
     [ -n "${PRINTER_OPTIONS}" ] || return 0
     if ! lpstat -p "${PRINTER_NAME}" >/dev/null 2>&1; then