test_as_completed(): disable "slow callback" warning
test_as_completed(): disable "slow callback" warning

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