Merging of @@rocksdb_skip_unique_check

Looking at how MariaDB should merge

ha_rocksdb::set_force_skip_unique_check(bool skip) 

and related code. This is code for

https://github.com/facebook/mysql-5.6/commit/bc4145e76dc34f576e3e468ca9d0fee35fe388d5
(changes @@rocksdb_skip_unique_check to @@rocksdb_debug_skip_unique_check )

which is a continuation of

https://github.com/facebook/mysql-5.6/commit/0998b17894c9e049d697a92fb0d9b79e597eb3c1
"Splitting rocksdb_bulk_load variable into two (#143)"
which added @@rocksdb_skip_unique_check

A question: why is there a need for rocksdb_debug_skip_unique_check if both MySQL and MariaDB support @@unique_checks variable?