Andreas, Please revert the Build-Depends: architecture-is-64-bit . I handled the RC side of this issue by removing liboobs and its reverse dependency gnome-system-tools from armel and armhf. It is ok in my opinion for this package to continue to fail to build on those architectures with this bug reopened.
Alternatively, you could ask for gnome-system-tools to be removed on i386. Otherwise, your liboobs upload will be unable to migrate to Testing. It looks like unfortunate timing. You might have missed my email to this bug since it was posted the same day you posted here that you were updating the packaging. Thank you, Jeremy Bícha
