Preserve the stack trace when CloneNotSupportedException impossibly happens.

git-svn-id: svn+ssh://src.earth.threerings.net/vilya/trunk@21 c613c5cb-e716-0410-b11b-feb51c14d237

src/java/com/threerings/parlor/game/data/GameConfig.java

@@ -146,7 +146,7 @@ public abstract class GameConfig extends PlaceConfig implements Cloneable
         try {
             return super.clone();
         } catch (CloneNotSupportedException cnse) {
-            throw new RuntimeException("clone() failed: " + cnse);
+            throw new RuntimeException(cnse);
         }
     }
 }