fix bug in src name regexp when using *org-babel-use-quick-and-dirty-noweb-expansion*

* lisp/ob.el (org-babel-expand-noweb-references): Fix bug in src name
  regexp when using *org-babel-use-quick-and-dirty-noweb-expansion*.

lisp/ob.el

@@ -2186,7 +2186,7 @@ block but are passed literally to the \"example-block\"."
 		    (when (org-babel-ref-goto-headline-id source-name)
 		      (org-babel-ref-headline-body)))
 		  ;; find the expansion of reference in this buffer
-		  (let ((rx (concat rx-prefix source-name))
+		  (let ((rx (concat rx-prefix source-name "[ \t\n]"))
 			expansion)
 		    (save-excursion
 		      (goto-char (point-min))