The problem with schroot is tracked in bug 1430557. The original reporter here already asked to close it, most other distros (all with systemd, including Fedora, SUSE, Arch, and most importantly Debian) now default to shared namespaces. Also, nspawn works perfectly well on Ubuntu and people are using it. Hence I still consider this "wontfix" -- let's fix schroot instead, which needs to happen anyway given that regardless of the distro default the admin can still set the default mount policy or individual mounts to being "shared".
** Changed in: systemd (Ubuntu) Status: New => Won't Fix -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1454057 Title: mounts are shared by default on ubuntu 15.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1454057/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs