This one was scheduled for removal in 2.3 since 2.2-dev3 by commit
1b85785bc ("MINOR: config: mark global.debug as deprecated"). Let's
remove it now. It remains totally possible to use -d on the command
line though.
22 regression tests for state machines are managed by the new
file tests/test-fsm.cfg. Check it, they are all documented
inside. Most of the bugs introduced during the FSM extraction
have been found with these tests.