Added more info about what the debug option does to the help and man. Upstream commit: https://github.com/upgrades-migrations/preupgrade-assistant/commit/aaa005342c44989acbd1845addcb92ea86674ac3
preupgrade-assistant-2.3.3-1.el6: man page and help still say exactly the same string as in comment 0.
Closing this bugzilla as the component is under a maintenance mode in which the maintainers are going to fix only critical bugs. If you consider the bugzilla critical, feel free to reopen the bug with an explanation.