performance improvement.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@5609 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/AbstractProject.java

@@ -246,6 +246,7 @@ public abstract class AbstractProject<P extends AbstractProject<P,R>,R extends A
      * Marks the build as disabled.
      */
     public void makeDisabled(boolean b) throws IOException {
+        if(disabled==b)     return; // noop
         this.disabled = b;
         save();
     }