- MFH '_' is valid in test blocks

run-tests.php

@@ -972,7 +972,7 @@ TEST $file
 		$line = fgets($fp);
 
 		// Match the beginning of a section.
-		if (preg_match('/^--([A-Z]+)--/', $line, $r)) {
+		if (preg_match('/^--([_A-Z]+)--/', $line, $r)) {
 			$section = $r[1];
 			$section_text[$section] = '';
 			$secfile = $section == 'FILE' || $section == 'FILEEOF';