Rpl_semi_sync_master_request_ack not showing result after stopping the ACK thread

In situation with 2 replicas where both are configured in semi-sync and when ack-thread is stopped Rpl_semi_sync_master_request_ack and we switch from slave to master, result returned is false empty value, while debugging it still holds proper value.
The PR 2374 introduced debug point pause_ack_thread_on_next_ack for testing pausing the ACK thread.
This same PR test failure is obtained in test 6, when rebasing from latest changes MDEV-32551.
Result before rebasing was as expected that value will be visible in SELECT and you can see that situation in commit result before rebase

show status like 'Rpl_semi_sync_master_request_ack';

Variable_name	Value

Rpl_semi_sync_master_request_ack	3

While, after rebase we have this result

connection master;

# Check request_ack right 

show variables like 'Rpl_semi_sync_master_request_ack';

Variable_name	Value

Debugging in gdb I have seen that this value is internally unchanged, but the client doesn't receive proper value, possible race condition.