[FUG-BR] The update metadata is correctly signed, but, failed an integrity check.

[Otacílio]

Estou pegando este erro quando tento atualizar uma máquina 9.1 
virtualizada em Virtual Box. Alguém sabe do que se trata?

[]'s
-Otacílio

root em ximbiriba:/usr/home/ota # freebsd-update -r 9.3-RELEASE upgrade
Looking up update.FreeBSD.org mirrors... 5 mirrors found.
Fetching metadata signature for 9.1-RELEASE from update2.freebsd.org... 
done.
Fetching metadata index... done.
Inspecting system... done.

The following components of FreeBSD seem to be installed:
kernel/generic src/src world/base world/lib32

The following components of FreeBSD do not seem to be installed:
world/doc world/games

Does this look reasonable (y/n)? y

Fetching metadata signature for 9.3-RELEASE from update2.freebsd.org... 
done.
Fetching metadata index... done.

The update metadata is correctly signed, but
failed an integrity check.
Cowardly refusing to proceed any further.
root em ximbiriba:/usr/home/ota #