The test fails because it reuses mysqltest perl code to copy directory
tree, and this code contains Windows-specific piece which outputs some
diagnostic information.
The patch introduces new parameter for that Windows-specific perl code to
have the ability to suppress diagnostic output on the corresponding
mysqltest perl module initialization.
The general reason why innodb redo log file is limited by 512G is that
log_block_convert_lsn_to_no() returns value limited by 1G. But there is no
need to have unique log block numbers in log group. The fix removes 512G
limit and limits log group size by
(uint32_t maximum value) * (minimum page size), which, in turns, can be
removed if fil_io() is no longer used for innodb redo log io.