Useless Forum Mappings
In the database, there are a few values in the vault_forummap table that probably result from another bug (fixed several betas ago) where the namespace ID was saved as a boolean when updating existing namespaces. That is, there are a bunch of 0s and 1s for namespace IDs, even though this should not be possible.
Fixed for the next build. The 0s were a result of zeroing deleted namespaces rather than just removing the map for them. The 1s are probably a result of the other bug and will be corrected by the upgrade script.