drop connections that come in between a close and an accept race
drop connections that come in between a close and an accept race

this is bad, but worse is the current logic which can sometimes hit a
nil counter channel.

lipengfeihb/grace,alvarolm/grace,beni55/grace,facebookgo/grace,davande/grace,latlontude/grace,toophy/grace,nigeldunn/grace,nordligulv/grace,sioncheng/grace