bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Juri Linkov <juri@linkov.net>]

> The *Help* buffer is still under Outline minor mode, although it now
> makes no sense, since there are no heading lines in the buffer.

But it has no adverse effect.  OTOH, when some Help command
will insert a heading line, then it will be handled automatically.
For example, 'C-h m' (describe-mode) could take advantage of
outline-minor-mode with heading lines for every displayed minor mode.

> The actual functions you use in "C-h f" don't matter; the point is
> that the Outline minor mode, once set by "C-h b", stays turned on in
> the *Help* buffers, instead of being reset when not needed.

If you still think it should be disabled everywhere outside of 'C-h b',
this could be fixed by such patch:

diff --git a/lisp/help-mode.el b/lisp/help-mode.el
index bf64d032b65..baf924ac8b4 100644
--- a/lisp/help-mode.el
+++ b/lisp/help-mode.el
@@ -498,6 +498,8 @@ help-setup-xref
 because we want to record the \"previous\" position of point so we can
 restore it properly when going back."
   (with-current-buffer (help-buffer)
+    (when (bound-and-true-p outline-minor-mode)
+      (outline-minor-mode -1))
     (when help-xref-stack-item
       (push (cons (point) help-xref-stack-item) help-xref-stack)
       (setq help-xref-forward-stack nil))