org-table: Fix formula correction when removing a hline

* lisp/org-table.el (org-table-kill-row): Do not correct formula when
  removing a hline.

Reported-by: alan.wehmann@gmail.com
<http://lists.gnu.org/archive/html/emacs-orgmode/2017-09/msg00429.html>

lisp/org-table.el

@@ -1646,12 +1646,14 @@ In particular, this does handle wide and invisible characters."
   (if (not (org-at-table-p))
       (user-error "Not at a table"))
   (let ((col (current-column))
-	(dline (org-table-current-dline)))
+	(dline (and (not (org-match-line org-table-hline-regexp))
+		    (org-table-current-dline))))
     (kill-region (point-at-bol) (min (1+ (point-at-eol)) (point-max)))
     (if (not (org-at-table-p)) (beginning-of-line 0))
     (org-move-to-column col)
-    (when (or (not org-table-fix-formulas-confirm)
-	      (funcall org-table-fix-formulas-confirm "Fix formulas? "))
+    (when (and dline
+	       (or (not org-table-fix-formulas-confirm)
+		   (funcall org-table-fix-formulas-confirm "Fix formulas? ")))
       (org-table-fix-formulas "@" (list (cons (number-to-string dline) "INVALID"))
 			      dline -1 dline))))