* image.el (image-type-from-buffer): Only return supported image type.

Fixes: debbugs:9045

lisp/ChangeLog

@@ -1,5 +1,8 @@
 2012-04-26  Chong Yidong  <cyd@gnu.org>
 
+	* image.el (image-type-from-buffer): Only return supported image
+	type (Bug#9045).
+
 	* vc/diff-mode.el (diff-beginning-of-hunk): Return a meaningful
 	value, for symmetry with diff-end-of-hunk.
 	(diff-split-hunk, diff-find-source-location)

lisp/image.el

@@ -282,7 +282,9 @@ be determined."
 		  types nil)
 	  (setq types (cdr types)))))
     (goto-char opoint)
-    type))
+    (and type
+	 (memq type image-types)
+	 type)))
 
 
 ;;;###autoload