Agenda: Try to speed up getting tags

lisp/ChangeLog

@@ -2,6 +2,7 @@
 
 	* org.el (org-store-link): No errors when getting custom id before
 	first headline.
+	(org-get-tags-at): Use `org-up-heading-safe' when getting tags.
 
 2009-04-23  Carsten Dominik  <carsten.dominik@gmail.com>
 

lisp/org.el

@@ -10596,7 +10596,7 @@ ignore inherited ones."
 				    tags)))
 		      (or org-use-tag-inheritance (throw 'done t))
 		      (if local (throw 'done t))
-		      (org-up-heading-all 1)
+		      (or (org-up-heading-safe) (error nil))
 		      (setq parent t)))
 		(error nil)))))
 	(append (org-remove-uniherited-tags org-file-tags) tags)))))