Description:
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When doing a stream_select(STDIN,null,null,0), then the return value will be 1 as soon as one switches the window focus or presses a meta key, but a subsequent fread(STDIN) will block.

This is possible the same problem as #42044, which was closed as not a bug - however, I deem this behaviour as a bug as the select() is supposed to make sure a fread() will NOT block!

Test script:
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public static function sleep($secs) {
		echo "sleeping $secs s";
		for($i=0;$i<$secs;$i++) {
			$a=array(STDIN);
			$b=NULL;
			$num=stream_select($a,$b,$b,0);
			if($num>0) { //read and discard
			echo "fd '$num'\n";
				echo "'".fread(STDIN,4096)."'";
				break;
			}
			echo "\r".str_repeat(" ",60)."\r";
			echo date("d.m.Y H:i:s") . " still sleeping for ".($secs-$i)." seconds";
			sleep(1);	
		}
		echo "done sleeping\n";
	}



Expected result:
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The sleep counter is supposed to keep on counting in the background even if the commandline window is not focused.

Actual result:
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The display will be e.g. "sleeping 20 sfd '1'" after focusing away.