Was playing with MDL-14093, and some days ago (last Sunday of March) I detected that DST changes, although finally are properly applied, they aren't changed on time.

In the related bug, experimenting with both Europe/Madrid and Australia/Perth times, they should have changed at 02:00 AM and 03:00 AM localtime respectively and I detected that:

1) Europe/Madrid was changed some (more than 1) hours before 02:00 AM (Madrid localtime)
2) Australia/Perth was changed some (more than 5) hours after 03:00 AM (Perth localtime)

I haven't researched more... but something is wrong about calculating when the DST must change. It seems that the server configuration (OS/Moodle) or so, affects the moment when DST are applied and that's wrong.

Ciao