/dev/pts being created with mode=600 by Lxc

I'm trying to set up a Centos 6 instance using lxc and it works fine except that non-root users cannot create pseudo-terminals under /dev/pts. After lots of googling, it appears that Lxc has reverted to an earlier bad behavior, in that /dev/pts is being created with the wrong permissions. I don't know yet whether this is an upstream regression or something specific to the Ubuntu setup. I can tell you that it has nothing to do with the fact that I am trying to run Centos6; I see exactly the same behavior with an Ubuntu 13.4 instance.

HOST
# fgrep pts /proc/mounts
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0

LXC instance
[root@rh64bare ~]# fgrep pts /proc/mounts
devpts /dev/console devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
devpts /dev/tty1 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
devpts /dev/tty2 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
devpts /dev/tty3 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
devpts /dev/tty4 devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
devpts /dev/pts devpts rw,relatime,mode=600,ptmxmode=666 0 0
devpts /dev/ptmx devpts rw,relatime,mode=600,ptmxmode=666 0 0

Note the mode on /dev/pts; only root can create pseudo terminals. I tried to add an explicit devpts line to the instance fstab with the correct parameters, but nothing changed. Additionally, /dev/pts is being created root/root, not root/tty, so the gid=5 (also missing from the /dev/pts options) would have no effect in any case.

Running Ubuntu 13.10 (but saw it with 13.4 as well).