Fix typo introduced in last, a=chris

diff --git a/src/models/GroupModel.php b/src/models/GroupModel.php
index 299e0e0db..6abcfe2fd 100644
--- a/src/models/GroupModel.php
+++ b/src/models/GroupModel.php
@@ -2451,7 +2451,7 @@ class GroupModel extends Model implements MediaConstants
             } else if (!$resource['is_dir'] &&
                 time() < $time + C\PAGE_TIMEOUT/2) {
                 $resource['has_thumb'] =
-                    $this->makeThumbStripExif $name, $folder, $thumb_folder);
+                    $this->makeThumbStripExif($name, $folder, $thumb_folder);
             }
             $resources[] = $resource;
         }