rb-site does a check to see if a dedup operation should be run. This

ends up checking some modern fields that didn't exist pre-1.7.
We now wrap this and catch the exception, handling the case where the

operation fails due to a database error. The assumption we make is that

if there's a database error, we're likely upgrading from a database that

doesn't have these columns, and a dedup is probably needed.

Ran an upgrade on a 1.5.x DB, and a 1.6.x DB. Both upgraded. Before this

change, they both gave errors about a missing column.