Bug#808364: lxc: lxc-start fails to mount proc (Operation not permitted)
I confirm that the problem exists and that downgrading to kernel version 3.16.7-ckt11-1+deb8u6 makes (unprivileged) container work again. I also found this bugreport in Ubuntu which may be related: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1519106 Tomassino
Bug#403122: Wrong copy_exec usage in initramfs-tools manpage
copy_exec /sbin/mdadm /sbin Tomassino Ferrauto pgpk32zHe9K3m.pgp Description: PGP signature