Index: src/wp-includes/link-template.php
===================================================================
--- src/wp-includes/link-template.php	(revision 28758)
+++ src/wp-includes/link-template.php	(working copy)
@@ -1655,7 +1655,7 @@
  *
  */
 function adjacent_posts_rel_link_wp_head() {
-	if ( ! is_single() ) {
+	if ( ! is_single() || is_attachment() ) {
 		return;
 	}
 	adjacent_posts_rel_link();