Bug #73744 rbr_exec_mode is not documented

Description:
rbr_exec_mode, present as a global and session variable on MySQL 5.7.4 is not documented on the release notes nor on http://dev.mysql.com/doc/refman/5.7/en/mysqld-option-tables.html (and equivalent places). I run into this when doing a diff between the configuration options of 5.6 and 5.7: http://dbahire.com/changes-in-configuration-of-global-variables-between-mysql-5-6-20-and-m... 

How to repeat:
Search for rbr_exec_mode on the release notes for MySQL 5.7 or its server variables reference. 

There are mentions of the IDEMPOTENT mode (here for NDB http://dev.mysql.com/doc/refman/5.7/en/replication-options-slave.html#sysvar_slave_exec_mo... and http://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-0.html for mysqlbinlog) but I only found the variable rbr_exec_mode documented on this developer blog: http://geek.rohitkalhans.com/2013/05/mysqlbinlog-idemmpotent-mode.html

Suggested fix:
Check when it was really added, add an entry on the release notes and document its usage on the server variables reference.

Thank you for the bug report.

Thanks for your feedback, this is now documented as follows:
rbr_exec_mode

This variable switches the server between IDEMPOTENT mode and STRICT mode. IDEMPOTENT mode causes suppression of duplicate-key and no-key-found errors. This mode is useful when replaying a row-based binary log on a server that causes conflicts with existing data. mysqlbinlog uses this mode when you set the --idempotent option by writing the following to the output:

SET SESSION RBR_EXEC_MODE=IDEMPOTENT;