fixed dirname

common/lib/capa/capa/inputtypes.py

@@ -873,7 +873,7 @@ class DragAndDropInput(InputTypeBase):
         self.to_render.add('drag_and_drop_json')
         try:  # for tests and mock up, work normally not in tets
             self.loaded_attributes['course_folder'] = \
-                self.system.location.split('/')[3]
+                self.system.filestore.root_path.split('/')[-1]
         except:
             self.loaded_attributes['course_folder'] = 'mock'
         self.to_render.add('course_folder')