Tudor,
This has been reported as bug#2951 with Ximian; see:
http://bugzilla.ximian.com/show_bug.cgi?id=2951
Also Ximian bug#2979 mentions this problem.
As for the Debian BTS, I found #62292 and #80739 seem to cover this too.
The latter mentions it was fixed with a NMU; this doesn't necessarily
solve the problem however if all it does is sets the packge to conflict
with the Ximian one.
::Gavin