E: installing Assembly /usr/lib/cli/gmime-sharp-2.2/gmime-sharp.dll failed

While setting up a new hybrid debian stable + backports, I got this strange error during a 'apt-get install gnome'.

$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 130 not upgraded.
2 not fully installed or removed.
After this operation, 0B of additional disk space will be used.
Setting up libgmime2.2-cil (2.2.22-2) ...
* Installing 1 assembly from libgmime2.2-cil into Mono
E: installing Assembly /usr/lib/cli/gmime-sharp-2.2/gmime-sharp.dll
failed
E: Installation of libgmime2.2-cil
with /usr/share/cli-common/runtimes.d/mono failed
dpkg: error processing libgmime2.2-cil (--configure):
subprocess installed post-installation script returned error exit
status 9
dpkg: dependency problems prevent configuration of tomboy:
tomboy depends on libgmime2.2-cil (>= 2.2.20); however:
Package libgmime2.2-cil is not configured yet.
dpkg: error processing tomboy (--configure):
dependency problems - leaving unconfigured
Errors were encountered while processing:
libgmime2.2-cil
tomboy
E: Sub-process /usr/bin/dpkg returned an error code (1)

This is already reported:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=520267