Bug in outlier detection where two different points with identical distances were missed, fixed

    counter = 0

    for i, group in matches.groupby('source_idx'):

        group_size = len(group)

        n_unique = len(group['destination_idx'].unique())

        # If we can not perform the ratio check because all matches are symmetrical

        if len(group['destination_idx'].unique()) == 1:

        if n_unique == 1:

            mask[counter:counter + group_size] = True

            counter += group_size

        else:

            # Otherwise, we can perform the ratio test

            sorted = group.sort_values(by=['distance'])

            unique = sorted['distance'].unique()

            if unique[0] < ratio * unique[1]:

            sorted_group = group.sort_values(by=['distance'])

            unique = sorted_group['distance'].unique()

            if len(unique) == 1:

                # The distances from the unique points are identical

                mask[counter: counter + group_size] = False

                counter += group_size

            elif unique[0] < ratio * unique[1]:

                # The ratio test passes

                mask[counter] = True

                mask[counter + 1:counter + group_size] = False

                counter += group_size