On Windows a named pipe server must call ConnectNamedPipe() before using
a named pipe. However, if the client has already connected then this
function returns a failure code, with detailed error code
ERROR_PIPE_CONNECTED. The server must check for this, as it means the
connection will work fine. The Java test that emulates what the C++
would do in production did not have this logic.
This was purely a test problem. The C++ code used in production already
does the right thing.
relates elastic/x-pack-elasticsearch#2359
Original commit: elastic/x-pack-elasticsearch@e162887f28