Hi Andreas, Indeed, the issue is in Horizon, which is fixed in unstable. I have fixed the dependency of manila-ui already for this issue, but the manila-ui package is still in Sid, not in Testing yet. Therefore, closing the bug is the way to go, so that manila-ui from Unstable migrates to Testing (as Horizon has already migrated to Testing).
Cheers, Thomas Goirand (zigo)