Comment 2 for bug 254266

There is no bug that I can see; your file system is possibly corrupted since the error is:

dpkg (subprocess): unable to execute post-installation script: Exec format error

coming from libgnome-cni, which is however fine if I check your arch/version in the archive.
Can you give this command in a terminal an attach here the resulting postinst file:

cat /var/lib/dpkg/info/libgnome-cni.postinst > postinst

?