Just to add that "shutdown -hP now" has been working as expected (→ computer is powered off) for the last 3 days. I'm now using that command from xfce4-terminal inside an X session and all the times was behaving correctly.
I will report for any change or new findings. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org