Downgrade assets db by removing the 'auto_close_date' column.

def _downgrade_v2(op):
    """
    Downgrade assets db by removing the 'auto_close_date' column.
    """
    # Drop indices before batch
    # This is to prevent index collision when creating the temp table
    op.drop_index('ix_equities_fuzzy_symbol')
    op.drop_index('ix_equities_company_symbol')

    # Execute batch op to allow column modification in SQLite
    with op.batch_alter_table('equities') as batch_op:
        batch_op.drop_column('auto_close_date')

    # Recreate indices after batch
    op.create_index('ix_equities_fuzzy_symbol',
                    table_name='equities',
                    columns=['fuzzy_symbol'])
    op.create_index('ix_equities_company_symbol',
                    table_name='equities',
                    columns=['company_symbol'])