fixup! switch-branch: prevent downgrades

updater/switch-branch/files/switch-branch

@@ -120,6 +120,10 @@ fetch_target_version() (
 		"Turris Mox")
 			board="mox"
 			;;
+                *)
+                        echo "Unknown device model: '$OPENWRT_DEVICE_PRODUCT'" >&2
+                        return 2
+                ;;
 	esac
 	curl "https://repo.turris.cz/$1/$board/lists/turris-version"
 )