Fix _UnixWritePipeTransport: raise BrokenPipeError when the pipe is closed
Fix _UnixWritePipeTransport: raise BrokenPipeError when the pipe is closed

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