Only enable CUI support when the message is valid.

Also the check if support isn't already enabled is not really needed, as it will just overwrite the field with the same value.

src/main/java/com/sk89q/worldedit/LocalSession.java

@@ -605,12 +605,9 @@ public class LocalSession {
     }
 
     public void handleCUIInitializationMessage(String text) {
-        if(!hasCUISupport()) {
-            setCUISupport(true);
-        }
-
         String[] split = text.split("\\|");
         if (split.length > 1 && split[0].equalsIgnoreCase("v")) { // enough fields and right message
+            setCUISupport(true);
             try {
                 setCUIVersion(Integer.parseInt(split[1]));
             } catch (NumberFormatException e) {