Index: core.drush.inc
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/drush/commands/core/core.drush.inc,v
retrieving revision 1.52
diff -u -r1.52 core.drush.inc
--- core.drush.inc	25 Nov 2009 04:40:59 -0000	1.52
+++ core.drush.inc	28 Nov 2009 19:47:34 -0000
@@ -397,7 +397,7 @@
     $all = array();
     foreach($searchpath as $key => $path) {
       $recurse = !$key == 'cwd';
-      $all = $all + array_keys(drush_scan_directory($path, '/\.php$/', array('.', '..', 'CVS'), NULL, $recurse));
+      $all = array_merge( $all , array_keys(drush_scan_directory($path, '/\.php$/', array('.', '..', 'CVS'), NULL, $recurse)) );
     }
     drush_print(implode("\n", $all));
   }