[beagleboard] BBB SYS_5V not dead on power off

I am powering a DC/DC converter on my cape with SYS_5V and just noticed that on toggling the
power button the machine does turn off, but there’s still about 2V on SYS_5V - why?
Using a 2A regulated power supply to power the unit.

That is because the PMIC driver is broken and I believe it will be fixed in V3.19

Regards,
John