bug#35996: User account password got locked when booting old generation

["pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de>]

On Sat, Jun 01, 2019 at 12:05:44AM +0200, Ludovic Courtès wrote:
> Did the old generation you booted have user ‘florian’?
> 

Yes, this is my main machine.  The users are the same.

> Also, how old was it?  User account management changed in March (commit
> 0ae735bcc8ff7fdc89d67b492bdee9091ee19e86).
>

The git commit for both old and new generation is

commit ad7466aafd7f166d0b6be5eb32dda1d3ee8a6445 (origin/master, origin/HEAD)
Author: Ludovic Court<C3><A8>s <ludo@gnu.org>
Date:   Sun May 26 23:18:21 2019 +0200

with unrelevant patches (for USB_ModeSwitch) applied on both, as well
as a non-working patch adding syslogd as a requirement to
udev-shepherd-service (making the generation unbootable and making
something display Stack overflow) and a working patch to add a --debug
argument to udevd for the new, unbootable generation.  The old
generation has a patch that adds wrong arguments to udevd that udevd
ignores.  All seems harmless.

I still cannot reproduce despite rebooting the broken generation
multiple times and then booting back into the old generation.

I wonder what would change /etc/shadow.

Regards,
Florian