xmonad crashes on start after upgrading to 11.10

[thearthur]

when upgrading from 11.04 to 11.10 the libffi5 package is deleated.

if you are upgrading and used xmonad on 11.04 then xmonad will try to use the already compiled
xmonad-x86_64-linux in ~/.xmonad that was build from xmonad.hs before the upgrade. This binary
will still be linked against the libffi5 package and will try to open libffi.so.5 and then crash because
the file does not exist.

    home/arthur/.xmonad/xmonad-x86_64-linux: error while loading shared libraries: libffi.so.5: cannot open shared object file: No such file or directory

this is easily fixed by logging in with unity and deleting the compiled files

rm ~/.xmonad/xmonad-x86_64-linux ~/.xmonad/xmonad.o ~/.xmonad/.hs

it would be nice if the post-install step of the .deb package would remove these compiled files on upgrade
with a command such as this:

rm -f /home/*/.xmonad/xmonad-x86_64-linux
rm -f /home/*/.xmonad/xmonad.o
rm -f /home/*/.xmonad/xmonad.hi

These could be cases where this fails to find users (with non-standard directories) and it may be safer to ensure that
~/.xmonad/xmonad.hs exists to ensure that the user is actually using xmonad (though this may not be required)

these already compiled binaries will never work and can always be automatically rebuilt to deleting them seems
both wise and safe, as well as much more convenient.

------------------------------------------------------
Description: Ubuntu 11.10
Release: 11.10
xmonad:
  Installed: 0.9.2-2build1
  Candidate: 0.9.2-2build1
  Version table:
 *** 0.9.2-2build1 0
        500 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe amd64 Packages
        100 /var/lib/dpkg/status

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Arne (RDS) (plexus)]

Note that on 32-bit systems it's

/home/*/.xmonad/xmonad-i386-linux

rather than

/home/*/.xmonad/xmonad-x86_64-linux