Consider the following situation:

* A
  Some text.
* B

- Place the cursor on A, press C-x n w (org-narrow-to-subtree).
- Go to the very end of the buffer and insert "xyz".
- C-x n w (widen).

You end up with:

* A
  Some Text
xyz* B


The attached one-line patch fixes this by passing `nil' for the
`to-heading' parameter of `org-end-of-subtree'.