update app.py

app.py

@@ -11,7 +11,7 @@ def test():
             r = requests.post(url, files = {'image' : f}, timeout=10)
             ret = json.loads(r.text)
         except Exception as e:
-            print('backend test failed')
+            print('backend test failed: ', str(e))
             return
 
     # image level cls score