bug#43300: [PATCH] Make M-x show new commands for obsolete aliases

[Juri Linkov]

>> Is the following sufficient?
>
> The old behavior was to never show obsolete commands in completion.  You
> could therefore only run one if you remembered and manually typed in the
> old name.  If you made a command obsolete, it would therefore just
> appear to disappear from one release to the next.
>
> The new behavior was intended to be less abrupt for cases where the old
> command is anyways just an alias for a new command.  In this way, we can
> more gently nudge users to use the new command instead.
>
> I therefore think we should revert back to the old behavior for commands
> that are obsolete without an alternative, that is we should not add such
> commands to the list of completion candidates.

Or maybe still some indication is needed to be displayed, even if there is
no alias for a new command.  Maybe display just " (obsolete)"?