 
     gotAllStudents: ->
       @withAllStudents (students) =>
+        #empty the array so this is idempotent, you can end up with too many rows
+        @rows.length = 0
         for student_id, student of students
           student.computed_current_score ||= 0
           student.computed_final_score ||= 0


      @postGradesStore.setGradeBookAssignments @assignments

    gotCourse: (course) =>
      @course = course


          gotAllStudents.resolve()

      gotCustomColumns = @getCustomColumns()
      @gotAllData = $.when(gotCustomColumns, gotAllStudents, @gotAllAssignmentGroupsPromise)

      @allSubmissionsLoaded.done =>
        for c in @customColumns
