What safety rule replaced the now-rescinded two-person rule (after Germanwings 9525)?
The French accident investigation board, Bureau d'Enquêtes et d'Analyses pour la sécurité de l'aviation civile (BEA), investigated this incident. The report was completed in March 2016. Among the recommendations for EASA was better medical and psychological monitoring by the aero medical examiners. Explicitly not recommended was the already mentioned practice of the two person rule, which leads to the security door being open too many times.

An aero medical examiner recommended that the pilot should have been committed to a mental facility two weeks before the incident. This fact only surfaced during the investigation. So his mental state was detected but because of lax institutional rules, nothing happened. The report can be found at bea.aero.