(org-insert-headline '(4)) should insert new headline before point

[York Zhao <gtdplatform@gmail.com>]

Hi list,

(org-insert-headline '(4)) used to insert new heading before point. But this had
broken recently. According to the docstring, this command inserts new
heading at the end of the parent subtree  ONLY if two universal prefix
arguments is given, not one. Here's the reproducer:

--8<---------------cut here---------------start------------->8---
emacs -Q -L path/to/org-mode/lisp/ --eval \
"(let ((buf (get-buffer-create \"test-org\")))
(with-current-buffer buf
(org-mode)
(insert \"* headline 1\")
(goto-char (line-beginning-position))
(org-insert-heading '(4)))
(switch-to-buffer buf))"
--8<---------------cut here---------------end--------------->8---

Thanks