Failed to get the result using mysqlbinlog flashback option on big binlog file

Failed to get the result using mysqlbinlog flashback option on large binlog file , failing case is as shown in the attachment pictures.
I've already figured it out - as long as the io_cache used within the flashback operation larger than 2147479552, which is the max value for read_buffer_size according to the mysql doc, flashback failure should happend.

I've created a pull request: https://github.com/MariaDB/server/pull/1214, please check

update at 2018.03.08:
Actually, I later realized that this bug was already fixed in release 10.3.13(seems like the same problem according to the commit message of mysys/mf_iocache.c) , but since it is not yet applied to branch 10.2, I still made this pull request , plus adding the required mtr test and result file.