Set the queue_len more consistently.

common/lib/capa/capa/inputtypes.py

@@ -659,7 +659,7 @@ class MatlabInput(CodeInput):
             self.queue_msg = self.input_state['queue_msg']
         if 'queuestate' in self.input_state and self.input_state['queuestate'] == 'queued':
             self.status = 'queued'
-            self.queue_len = '1'
+            self.queue_len = 1
             self.msg = self.plot_submitted_msg
 
 
@@ -702,7 +702,7 @@ class MatlabInput(CodeInput):
     def _extra_context(self):
         ''' Set up additional context variables'''
         extra_context = {
-                'queue_len': self.queue_len,
+                'queue_len': str(self.queue_len),
                 'queue_msg': self.queue_msg
                 }
         return extra_context