In irc.cpp there is a function bool RecvLine(SOCKET hSocket, string& strLine)

The function, when fails, outputs messages like printf("IRC socket closed\n"); and printf("IRC recv failed: %d\n", nErr);.

Sadly that function is used even outside of IRC: from net.cpp's GetMyExternalIP2().

The easiest solution is to ignore it :-)
The easy solution is to take away the "IRC " part from the error message.
Another easy solution is to duplicate the function.
The more complex solution is to pass a parameter about the connection type to RecvLine.