I do not know a solution for this behavior but you do not need aptitude
in this situation you can do apt-get dist-upgrade to fix those upgrades
that get held back for various reasons.

> Date: Fri, 28 Aug 2015 08:45:51 +0100
> From: Dave Turner<dave_t_turner@???>
> To:dng@???
> Subject: [DNG] strange characters when using 'examine' in aptitude
> Message-ID:<55E011AF.6050600@???>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I run devuan unstable 'ceres' on my Toshiba laptop and my iMac.
> It all works with just a bit of weirdness.
> I use apt-get update apt-get upgrade and then use aptitude to fix those
> upgrades that get held back for various reasons.
> Whenever I highlight one of the held back packages and press 'e' to
> examine the various possibilities the names of the packages to be
> removed or installed are mangled with block characters and/or assorted
> characters from other non-Latin1 character sets. Upside down question
> marks etc.
>
> Any ideas what is going on?
>
> I am using the slim login manager and then depending on my mood fluxbox,
> xfce, or lumina - the new desktop from pc-bsd.