bug#47215: [External] : bug#47215: 28.0.50; Let M-x switch between M-x and M-X

[Drew Adams <drew.adams@oracle.com>]

> > Finally, the docstring says initial-input is deprecated.
> 
> I think this use case demonstrates that perhaps we should slightly
> un-deprecate initial-input -- instead of deprecating it, we could
> instead just discourage the usage.

It never should have been deprecated - quite unwise.
Arguments against deprecation went unheeded/ignored.
___

The Icicles doc for `completing-read' has always said:

 If INITIAL-INPUT is non-nil, insert it in the minibuffer initially,
 with point positioned at the end.  If it is (STRING . POSITION), the
 initial input is STRING, but point is placed at zero-indexed position
 POSITION in STRING.  (This is different from `read-from-minibuffer'
 and related functions, which use one-indexing for POSITION.)

 INITIAL-INPUT is considered deprecated by vanilla Emacs, but not by
 Icicles.  If INITIAL-INPUT is nil and DEF is non-nil, the user can use
 `next-history-element' to yank DEF into the minibuffer.
___

As for your `M-x' changes and the addition of `M-X':
they too aren't positive, IMO, but I'll leave it to
time and others for that to be realized.  (I already
mentioned better approaches in the "Smarter M-x"
thread.)