Fix diff view mistakenly reporting that ES has been dropped from a course

application/library/View/Helper/BulletinEntryDiff.php

@@ -9,7 +9,7 @@ class Application_View_Helper_BulletinEntryDiff
         // ES and IS
         $currentES = ($currentCourse->isEssentialStudies() == true ? '[ES]' : '');
         $proposedES = ($proposedCourse->isEssentialStudies() == true ? '[ES]' : '');
-        $diffES = $this->_getDiffText($currentES, $proposedIS);
+        $diffES = $this->_getDiffText($currentES, $proposedES);
 
         $currentIS = ($currentCourse->integratedStudies == 'yes' ? '[IS]' : '');
         $proposedIS = ($proposedCourse->integratedStudies == 'yes' ? '[IS]' : '');