Back in 2008 (in commit 2c45dbbb5f), some retail code incrementing `Player->failures_this_session` was removed, seemingly by accident. A month later, a bug related to this was fixed (in commit 28a408deee) in a different way. Since this fix is rendered redundant by the restoration of the original behavior, I've removed it and put back in the old behavior. This is only "mostly-retail" because the retail code didn't check `Game_mode & GM_CAMPAIGN_MODE`.