When an option is set but not defined, just don't set the value

astronaut/astronaut

@@ -163,9 +163,13 @@ option() {
 
     local enabled=false
     local opt
-    local IFS=','; for opt in $options; do
-        local option="$(echo "$opt" | cut -d '=' -f 1)"
-        local value="$(echo "$opt" | cut -d '=' -f 2)"
+    local IFS=','; for option in $options; do
+        case "$option" in
+            *=*)
+                local value="$(echo "$option" | cut -d '=' -f 2)"
+                local option="$(echo "$option" | cut -d '=' -f 1)"
+                ;;
+        esac
 
         if [ "$option" = "$check" ]; then
             local enabled=true