Xulrunner-8.0 fails to install

[mailinglists at peterspages.nl]

Tried to upgrade to Iceweasel 8 on Debian Squeeze today, this failed 
because of xulrunner giving the following (dutch) error:

(Database inlezen ... 124045 files and directories currently 
installed.)
Uitpakken van xulrunner-8.0 (uit 
.../xulrunner-8.0_8.0-1~bpo60+1_i386.deb) ...
dpkg (subproces): unable to execute nieuw pre-installation script 
(/var/lib/dpkg/tmp.ci/preinst): Verkeerd uitvoerbaar bestand
dpkg: fout bij afhandelen van 
/var/cache/apt/archives/xulrunner-8.0_8.0-1~bpo60+1_i386.deb (--unpack):
  subproces nieuw pre-installation script gaf een foutwaarde 2 terug
configured to not write apport reports
                                       Fouten gevonden tijdens 
behandelen van:
  /var/cache/apt/archives/xulrunner-8.0_8.0-1~bpo60+1_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

Regards
Peter