Stats are not dropped for ALTER TABLE ... MODIFY ..., ALGORITHM=COPY

SET histogram_type = DOUBLE_PREC_HB;

CREATE TABLE t (a INT);

INSERT INTO t VALUES (1),(2);

ANALYZE TABLE t PERSISTENT FOR ALL;

select db_name, table_name, min_value, max_value, hex(histogram) from mysql.column_stats where table_name='t';

ALTER TABLE t MODIFY a BLOB, ALGORITHM=COPY;

select db_name, table_name, min_value, max_value, hex(histogram) from mysql.column_stats where table_name='t';

SELECT a FROM t WHERE a LIKE '1%';

DROP TABLE t;

// in mysql_alter_table:

  if (alter_info->algorithm(thd) != Alter_info::ALTER_TABLE_ALGORITHM_COPY)

  {

//  [... 8 lines elided]

    /* Fill the Alter_inplace_info structure. */

    if (fill_alter_inplace_info(thd, table, &ha_alter_info))

// in fill_alter_inplace_info:

      /*

        Check if type of column has changed.

      */

      bool is_equal= field->is_equal(*new_field);

//  [... 24 lines elided]

      if (!is_equal)

      {

        if (field->table->file->can_convert_nocopy(*field, *new_field))

//  [... 8 lines elided]

        else

        {

          /* New column type is incompatible with old one. */

          ha_alter_info->handler_flags|= field->stored_in_db()

                                             ? ALTER_STORED_COLUMN_TYPE

                                             : ALTER_VIRTUAL_COLUMN_TYPE;

          if (table->s->tmp_table == NO_TMP_TABLE)

          {

            if (alter_info->drop_stat_fields.push_back(field, thd->mem_root))

              DBUG_RETURN(true);