Clean up test_cancel_race().
Clean up test_cancel_race().

haypo/trollius,1st1/asyncio,vxgmichel/asyncio,manipopopo/asyncio,gsb-eng/asyncio,vxgmichel/asyncio,manipopopo/asyncio,Martiusweb/asyncio,haypo/trollius,jashandeep-sohi/asyncio,fallen/asyncio,gvanrossum/asyncio,gvanrossum/asyncio,jashandeep-sohi/asyncio,ajdavis/asyncio,vxgmichel/asyncio,fallen/asyncio,1st1/asyncio,gsb-eng/asyncio,1st1/asyncio,gsb-eng/asyncio,manipopopo/asyncio,ajdavis/asyncio,jashandeep-sohi/asyncio,haypo/trollius,ajdavis/asyncio,fallen/asyncio,gvanrossum/asyncio,Martiusweb/asyncio,Martiusweb/asyncio