ER_HOST_IS_BLOCKED returns packet sequence 1 instead of 0

I discovered this while trying to debug the go client library.
https://github.com/go-sql-driver/mysql/issues/1038

I wrote some scripts to repeat the issue: https://github.com/koshatul/go-mysql-sync-issue

It only affected MariaDB 10.2+ where the 4th byte of the packet that is sequence is returning 1 instead of 0 when the host is blocked.

Example:
Sending 100 broken connections first to trigger the ER_HOST_IS_BLOCKED

10.0 and 10.1:

01101000 00000000 00000000 00000000

10.2, 10.3, 10.4:

01101000 00000000 00000000 00000001