wait and retry if the server state is "upgrading" when calling NextWriter. This is a fix to https://github.com/googollee/go-socket.io/issues/52
wait and retry if the server state is "upgrading" when calling NextWriter.
This is a fix to https://github.com/googollee/go-socket.io/issues/52

Possum3D/go-engine.io,ym/go-engine.io,DisruptiveMind/go-engine.io,ym/go-engine.io,jmptrader/go-engine.io,lotrfan/go-engine.io,zhouhui8915/go-engine.io,Possum3D/go-engine.io,zhouhui8915/go-engine.io,Possum3D/go-engine.io,zhouhui8915/go-engine.io,lotrfan/go-engine.io,DisruptiveMind/go-engine.io,ym/go-engine.io,lotrfan/go-engine.io,jmptrader/go-engine.io,jmptrader/go-engine.io,DisruptiveMind/go-engine.io