bug#48404: 28.0.50; "Invalid version syntax" errors with read-extended-command

[Eli Zaretskii <eliz@gnu.org>]

> From: Tassilo Horn <tsdh@gnu.org>
> Date: Thu, 13 May 2021 22:45:01 +0200
> Cc: Stefan Kangas <stefan@marxist.se>
> 
> Since commit 1af91d271e077134e272055407fb8c4312a7579b I get strange
> "Invalid version syntax: <package> <version> (must start with a number)"
> errors during M-x completion in the minibuffer.  I can't reproduce with
> emacs -Q but in the error, <package> is always some (M)ELPA package.
> 
> For example, M-x mag TAB gives
> 
>   completion--some: Invalid version syntax: ‘Magit 3.0.0’ (must start with a number)

That commit uses byte-obsolete-info property of a symbol, and expects
its caddr to be a valid version number.  It sounds like in some cases
it is not an Emacs version, but something else.  So, questions:

  . can you find out what kind of value does the byte-obsolete-info
    property is there on Magit functions? and
  . how come these properties were added to something that is not an
    Emacs core code?

In any case, it sounds like blindly trusting the value of that
property is not a good idea, and we should wrap the call to
version-to-list there in condition-case.  Could you try that?