Make set_status_header() a dummy under CLI

Close #3605
diff --git a/system/core/Common.php b/system/core/Common.php
index 9f50974..7035c18 100644
--- a/system/core/Common.php
+++ b/system/core/Common.php
@@ -492,6 +492,11 @@
 	 */
 	function set_status_header($code = 200, $text = '')
 	{
+		if (is_cli())
+		{
+			return;
+		}
+
 		$stati = array(
 			200	=> 'OK',
 			201	=> 'Created',