update named code block regexp for indentation

Previously didn't work if #+header lines intervening between the
  name and the block were indented.

lisp/ob-core.el

@@ -581,7 +581,7 @@ can not be resolved.")
 (defun org-babel-named-src-block-regexp-for-name (name)
   "This generates a regexp used to match a src block named NAME."
   (concat org-babel-src-name-regexp (regexp-quote name)
-	  "[ \t(]*[\r\n]\\(?:^#.*[\r\n]\\)*"
+	  "[ \t(]*[\r\n]\\(?:^[[:space:]]*#.*[\r\n]\\)*"
 	  (substring org-babel-src-block-regexp 1)))
 
 (defun org-babel-named-data-regexp-for-name (name)