Why do the db transaction methods snuff exceptions?

While browsing ActiveRecord::ConnectionAdapters::MysqlAdapter (Rails
1.2.5), I see:

      def commit_db_transaction #:nodoc:
        execute "COMMIT"
      rescue Exception
        # Transactions aren't supported
      end

      def rollback_db_transaction #:nodoc:
        execute "ROLLBACK"
      rescue Exception
        # Transactions aren't supported
      end

Why does Rails snuff these exceptions? Why not raise a
TransactionsNotSupportedException? I would think it very important to
know if a COMMIT or ROLLBACK fails.

Thanks,

Brian Hartin