To the documentor: The DEFAULT value in SHOW COLUMNS/SELECT FROM I_S.COLUMNS
was truncated to NAME_LEN (which effectively is 64) characters.


mysql-test/r/information_schema.result:
  Update result
  
  Because the length of I_S.COLUMNS.COLUMN_DEFAULT was increased to
  65535 the column changed it's type from varchar(64) to longtext
  The type is longtext if the length is > 65532 (the max varchar len)
mysql-test/t/information_schema.test:
  test case for bug#23037: Bug in field "Default" of
  query "SHOW COLUMNS FROM table"
  
  Both SHOW COLUMNS and I_S.COLUMNS is TESTED as well the
  value returned by both. Using --replace_regex is unfeasible
  as the repetition value cannot be > 255.
  --replace_regex /A{256}/VALUE/ doesn't work, not to talk about
    /A{65532}/VALUE/
  /(A{255}){255}/VALUE/ is awfully slow. Thus, simple function with
  cursor is used to extract the value.
sql/sql_show.cc:
  Default value can have TIMESTAMP, CHAR, VARCHAR, ENUM
  VARCHAR can have the longest value, up to 65535. However, because
  of table handler limitations the actual limit is 65532 characters,
  latin1 charset. However, here is used MAX_FIELD_VARCHARLENGTH macro,
  because there could be a storage engine without such limitation.