refs #134 Use an alternate transaction to create the source cursor when
copying databases. If the source host is localhost, this will ensure
that the transaction doing the query (and thus getMore(), passing txn
ownership to the cursor) will different than the transaction doing
inserts for copy. We have to play a careful game with cc().txn()
and set it appropriately around writes, restoring it before calling
cursor->more(). Hopefully we have a better pattern for fixing issues
like this in the future.