RuntimeError: Set changed size during iteration

[vovapi]

When running yandex-tank with yatank-online report plugin i got this error:

      INFO:yandextank.core.consoleworker:Exception: Traceback (most recent call last):
        File "/usr/local/lib/python2.7/dist-packages/yandextank/core/consoleworker.py", line 277, in perform_test
          retcode = self.core.wait_for_finish()
        File "/usr/local/lib/python2.7/dist-packages/yandextank/core/tankcore.py", line 302, in wait_for_finish
          retcode = plugin.is_test_finished()
        File "/usr/local/lib/python2.7/dist-packages/yandextank/plugins/Aggregator.py", line 75, in is_test_finished
          self.__read_samples(2)
        File "/usr/local/lib/python2.7/dist-packages/yandextank/plugins/Aggregator.py", line 122, in __read_samples
          self.__notify_listeners(data)
        File "/usr/local/lib/python2.7/dist-packages/yandextank/plugins/Aggregator.py", line 94, in __notify_listeners
          listener.aggregate_second(data)
        File "/usr/local/lib/python2.7/dist-packages/yatank_online-0.0.2-py2.7.egg/yatank_OnlineReport/plugin.py", line 80, in aggregate_second
          self.server.send(message)
        File "/usr/local/lib/python2.7/dist-packages/yatank_online-0.0.2-py2.7.egg/yatank_OnlineReport/server.py", line 117, in send
          for connection in Client.CONNECTIONS:
      RuntimeError: Set changed size during iteration