bug#19012: 25.0.50; `help-window-select'

[Drew Adams]

> > Clearly you just want to be snarky and not read what I wrote,
> > which is that **when `display-buffer' uses
> > `special-display-function'** there is no such restriction.
> 
> Of course special-display-function can do whatever it wants,
> but if it doesn't follow the behavior described by
> display-buffer's docstring, it may break some callers.

The behavior specified by display-buffer's doc string is just
whatever `special-display-function' does - nothing more or less,
when `special-display-function' is used.

So there is *no* behavior for `special-display-function' for
to follow, other than its own behavior.  `display-buffer' says
nothing about `display-buffer' behavior in this case - it
says only that it delegates `display-buffer' behavior to
`special-display-function'.  That's the point of providing
for `special-display-function'.