ob: Don't allow #+header lines to prevent block finding

* lisp/ob.el (org-babel-where-is-src-block-head): Skip over
intervening #+header lines when searching for block associated with
block name line.

lisp/ob.el

@@ -1100,8 +1100,11 @@ If the point is not on a source block then return nil."
     (or
      (save-excursion ;; on a source name line
        (beginning-of-line 1)
-       (and (looking-at org-babel-src-name-regexp) (forward-line 1)
-            (looking-at org-babel-src-block-regexp)
+       (and (looking-at org-babel-src-name-regexp)
+	    (progn
+	      (while (and (forward-line 1)
+			  (looking-at org-babel-multi-line-header-regexp)))
+	      (looking-at org-babel-src-block-regexp))
             (point)))
      (save-excursion ;; on a #+begin_src line
        (beginning-of-line 1)