Fix sorting for files that only differ in case.

lib/private/naturalsort_defaultcollator.php

@@ -13,8 +13,11 @@ class NaturalSort_DefaultCollator {
 	public function compare($a, $b) {
 		$result = strcasecmp($a, $b);
 		if ($result === 0) {
+			if ($a === $b) {
 				return 0;
 			}
+			return ($a > $b) ? -1 : 1;
+		}
 		return ($result < 0) ? -1 : 1;
 	}
 }