def filter_backtrace(backtrace, &line_handler)
      backtrace.reverse_each do |bt|
        yield bt unless (bt =~ /(\/lib\/riot|rake_test_loader)/)
      end
    end
Filters Riot and Rake method calls from an exception backtrace.

@param [Array] backtrace an exception's backtrace
@param [lambda] &line_handler called each time a good line is found