The length of extra_data is calculated inconsistent with the document

[lifani]

In the document "https://dev.mysql.com/doc/internals/en/rows-event.html#packet-Binlog::RowsEventExtraData" the length of extra_data is calculated as [extra_data_len - 2], but in the rows_event.py is calculated as [extra_data_len / 8]。Why？

[baloo]

no idea, but feel free to throw a PR to fix that :)

[dongwook-chan]

@lifani
This issue was fixed in #355 and released in version 0.26.