tweaks to link for image subsearch 3, a=chris

diff --git a/src/views/helpers/ImagesHelper.php b/src/views/helpers/ImagesHelper.php
index 96ec2239d..80e6aab67 100644
--- a/src/views/helpers/ImagesHelper.php
+++ b/src/views/helpers/ImagesHelper.php
@@ -58,7 +58,9 @@ class ImagesHelper extends Helper implements CrawlConstants
             if ($image_subsearch) {
                 $query .= '&s=images';
             } else {
-                $query .= '%20media:image';
+                if (!stristr($query, media:image)) {
+                    $query .= '%20media:image';
+                }
             }
             ?>
             <h2><a href="<?= $query ?>"