This is caused by bug 804600 A no-change rebuild against dh-strip-nondeterminism 0.014-1 (the current version in Sid) will fix the problem.
The problem is introduced at build time, and definitely affects virtuoso-opensource in Sid currently. * Installing 1 assembly from libvirtuoso5.5-cil into Mono E: installing Assembly /usr/lib/cli/virtuoso-5.5/OpenLink.Data.Virtuoso.dll failed E: Installation of libvirtuoso5.5-cil with /usr/share/cli-common/runtimes.d/mono failed dpkg: error processing package libvirtuoso5.5-cil (--configure): subprocess installed post-installation script returned error exit status 29