Change key_from_fd to log warning and return None if key not found.
Change key_from_fd to log warning and return None if key not found.

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