Single broken package blocks whole package management

[Urs Thuermann <urs@isnogud.escape.de>]

After an dist-upgrade from Raspian 8 (jessie) to 9.13 (stretch)
hundreds of packages still need to be upgraded and aptitude reports
numerous conflicts.

I first wanted to upgrade everything which doesn't causes any
conflicts, which fails because of problems in wolfram-engine:

    root@uranus:~# aptitude safe-upgrade --no-new-installs -RZ
    Resolving dependencies...                
    open: 2242; closed: 1906; defer: 121; conflict: 311
    The following packages will be upgraded:
      acl <+36.9 kB>  adduser <-222 kB>  alacarte <-20.5 kB>  
      alsa-utils <+198 kB>  aspell-en <+95.2 kB>  avahi-daemon <+53.2 kB>  
      [...]
      xserver-common <+53.2 kB>  xserver-xorg <+1024 B>  
      xserver-xorg-input-all <+1024 B>  xterm <+163 kB>  
    The following partially installed packages will be configured:
      debconf-utils  
    The following packages are RECOMMENDED but will NOT be installed:
      at-spi2-core  bsd-mailx  cinnamon  dunst  exfat-utils  fonts-piboto  
      gdisk  gnome-accessibility-themes  gnome-flashback  gnome-screenshot
      [...]
      xfce4-notifyd  xfonts-base  xserver-xorg-input-wacom  
      xserver-xorg-legacy  
    663 packages upgraded, 0 newly installed, 0 to remove and 344 not upgraded.
    Need to get 0 B/283 MB of archives. After unpacking 89.8 MB will be used.
    Do you want to continue? [Y/n/?] 
    Reading changelogs... Done               
    Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^(.*?)(\\)?\${ <-- HERE ([^{}]+)}(.*)$/ at /usr/share/perl5/Debconf/Question.pm line 72.
    Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/\${ <-- HERE ([^}]+)}/ at /usr/share/perl5/Debconf/Config.pm line 30.
    Extracting templates from packages: 100%
    Preconfiguring packages ...
    dpkg: unrecoverable fatal error, aborting:
     files list file for package 'wolfram-engine' contains empty filename
    E: Sub-process /usr/bin/dpkg returned an error code (2)
    Failed to perform requested operation on package.  Trying to recover:

    root@uranus:~#

I tried to remove packages wolfram-engine and wolframscript, also
tried to remove debconf-utils, but everything fails with the same
error message:

    root@uranus:~# dpkg --force-all -P wolfram-engine 
    dpkg: unrecoverable fatal error, aborting:
     files list file for package 'wolfram-engine' contains empty filename

Also, upgrading a single package that's completely unrelated, is not
possible:

    root@uranus:~# aptitude install acl
    The following packages will be upgraded: 
      acl libacl1 
    The following partially installed packages will be configured:
      debconf-utils{b} 
    2 packages upgraded, 0 newly installed, 0 to remove and 1005 not upgraded.
    Need to get 0 B/80.7 kB of archives. After unpacking 49.2 kB will be used.
    The following packages have unmet dependencies:
     debconf-utils : Depends: debconf (= 1.5.61) but 1.5.56+deb8u1 is installed and it is kept back.
    The following actions will resolve these dependencies:

         Remove the following packages:
    1)     debconf-utils               



    Accept this solution? [Y/n/q/?] 
    The following packages will be REMOVED:
      debconf-utils{a} 
    The following packages will be upgraded:
      acl libacl1 
    2 packages upgraded, 0 newly installed, 1 to remove and 1005 not upgraded.
    Need to get 0 B/80.7 kB of archives. After unpacking 58.4 kB will be freed.
    Do you want to continue? [Y/n/?] 
    Reading changelogs... Done               
    Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^(.*?)(\\)?\${ <-- HERE ([^{}]+)}(.*)$/ at /usr/share/perl5/Debconf/Question.pm line 72.
    Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/\${ <-- HERE ([^}]+)}/ at /usr/share/perl5/Debconf/Config.pm line 30.
    dpkg: unrecoverable fatal error, aborting:
     files list file for package 'wolfram-engine' contains empty filename
    E: Sub-process /usr/bin/dpkg returned an error code (2)
    Failed to perform requested operation on package.  Trying to recover:

    root@uranus:~#
    
What else can I do to get the package management working again?

urs