twisted.web.distrib leaks references maybe

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Seen at  http://twistedmatrix.com/highscores/

[Failure instance: Traceback: <class 'twisted.spread.pb.Error'>: Maximum PB reference count exceeded.
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/web/server.py:132:process
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/web/server.py:167:render
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/web/distrib.py:205:render
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/pb.py:364:callRemote
--- <exception caught here> ---
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/pb.py:879:_sendMessage
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/pb.py:833:serialize
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/jelly.py:1137:jelly
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/jelly.py:532:jelly
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/jelly.py:586:_jellyIterable
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/jelly.py:473:jelly
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/flavors.py:301:jellyFor
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/jelly.py:536:jelly
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/jelly.py:473:jelly
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/flavors.py:127:jellyFor
/srv/pypy/pypy-c-jit-43780-b590cf6de419-linux/site-packages/twisted/spread/pb.py:736:registerReference
]