ConsoleReaderChildProcess: die voluntarily if connection to server process is closed

this happens if the parent process is killed via SIGINT, because its stdin will be closed, interrupting a blocking read. This might also happen if the user pressed CTRL+D, so we don't die unless end of socket stream was also detected.

closes #4335

src/console/ConsoleReaderChildProcess.php

@@ -41,7 +41,7 @@ if($socket === false){
 	throw new \RuntimeException("Failed to connect to server process");
 }
 $consoleReader = new ConsoleReader();
-while(true){
+while(!feof($socket)){
 	$line = $consoleReader->readLine();
 	if($line !== null){
 		fwrite($socket, $line . "\n");