The "# never reach here" line is reached on the parent process when the input stream reaches EOF (which might involve typing ^D if the input stream is the terminal). Assuming that "# never reach here" is the end of the script, falling past it implicitly closes the socket from the parent side, which will cause the child process to see EOF on the socket. The child then hits the "# never reach here" line.

Unless I'm missing some subtle point, the "# never reach here" comment is a lie.