Debian Stretch. uname -r: 4.5.0-2-amd64
Broken: Latest Linux 64 glibc219 buildbot build, as of writing.
DCI-P3 didn't seem to be showing. So I looked at config.ocio.
It would seem that an old (2012) commit (07082fb7d050) renamed DCIP3 in displays to DCI-P3 in config.ocio, without updating the active_displays setting properly (which currently lists DCIP3, not DCI-P3). This results in DCI-P3 not showing up in Scene-Color Management.
Exact steps for others to reproduce the error: Open any Blender file. Try to find DCI-P3 as a Display Device in Scene-->Color Management. It's not there!
This fix is simply to add the - back in config.ocio. I also added a Default (Academy RRT) for it, which it was missing.