bug#61733: emacs-dump-portable fails in 29.0.60

[Eli Zaretskii]

> From: Lynn Winebarger <owinebar@gmail.com>
> Date: Thu, 23 Feb 2023 17:48:19 -0500
> Cc: 61733@debbugs.gnu.org
> 
> On Thu, Feb 23, 2023 at 9:50 AM Eli Zaretskii <eliz@gnu.org> wrote:
> > > From: Lynn Winebarger <owinebar@gmail.com>
> > > Date: Thu, 23 Feb 2023 07:55:53 -0500
> > >
> > > These issues make switching to 29.1 a non-starter for users relying on
> > > redumping to make startup time reasonable.
> >
> > No one should be relying on redumping, because Emacs does not (yet)
> > support that.
> 
> In what sense?

In the sense that it doesn't yet work reliably.  If it works for
someone, it's sheer luck.  E.g., see this:

  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=34936#16

> The normal-top-level function is brittle, as is the system for setting
> customization variables at startup.  But those issues are separate
> from the redumping functionality, by which I only mean invoking
> dump-emacs-portable outside of dump-mode.

They are not separate, they are all part of a large problem: some
initialization code in Emacs doesn't support multiple restarts.