org.el (org-paste-subtree): Remove useless (concat ...).

* org.el (org-paste-subtree): Remove useless (concat ...).

See change from Stefan Monnier here:
https://lists.gnu.org/archive/html/emacs-diffs/2011-09/msg00224.html

lisp/org.el

@@ -7576,7 +7576,7 @@ the inserted text when done."
   (org-with-limited-levels
    (let* ((visp (not (outline-invisible-p)))
 	  (txt tree)
-	  (^re_ (concat "\\(\\*+\\)[  \t]*"))
+	  (^re_ "\\(\\*+\\)[  \t]*")
 	  (old-level (if (string-match org-outline-regexp-bol txt)
 			 (- (match-end 0) (match-beginning 0) 1)
 		       -1))