append_file in mysqltest does not support variables and expressions substitution

  DESCRIPTION

  append_file <file_name> [<delimiter>];

  <what to write line 1>

  <...>

  < what to write line n>

  EOF

  --append_file <file_name>;

  <what to write line 1>

  <...>

  < what to write line n>

  EOF

  Append everything between the "append_file" command

  and 'delimiter' to "file_name"

  Default <delimiter> is EOF