Index: course/edit.php
===================================================================
--- course/edit.php	(revision 16425)
+++ course/edit.php	(working copy)
@@ -132,6 +132,12 @@
         }
     } else {
         // Save any changes to the files used in the editor
+        if (!has_capability('moodle/course:changesummary', $coursecontext)) {
+            // summary_editor won't work with setConstant() and summaryformat can't be null
+            // so be sure it's set here when user does not have permission to edit summary
+            $data->summary_editor["text"] = $course->summary;
+            $data->summary_editor["format"] = $course->summaryformat;
+        }
         update_course($data, $editoroptions);
     }