[DRE-maint] Bug#956964: schleuder: using x-attach-listkey with emails from Thunderbird and protected headers fails

[Georg Faerber]

Package: schleuder
Version: 3.4.0-1
Forwarded: https://0xacab.org/schleuder/schleuder/-/commit/7a3f3c9ba9494c86a44faba0fa9f203cc64eb666
Tags: fixed-upstream

Using x-attach-listkey with emails created by Thunderbird and protected
headers fails. The output is garbled and not usable.

A fix was released upstream.