Greeter: Password check doesn't work when changing first entry

Originally created by @mercedes508 on #13447 (Redmine)

In Tails 3.0.1 (and previous), at Greeter, when setting an administration password the following way, you don’t get any error message, but can’t get and admin terminal neither:

Procedure
=

• go to the admin password part of the Greeter
• in the first field type your password, but wrongly (let’s say “possword”)
• in the second field type the right one (let’s say “password”)

You get a notice that it doesn’t match

• change the password in the first field to the right one (“password”)

You get a notice that it matches

• Start Tails

Result
==

Can’t open/use an admin password.

Feature Branch: https://salsa.debian.org/tails-team/tails/merge_requests/39/commits

Related issues

• Related to #12386 (closed)
• Related to #14544 (closed)
• Blocked by #16095 (closed)