Bug#939649: /usr/bin/systemd-nspawn: systemd-nspawn fails with "Failed to register machine: Unit -.mount is masked."

[Nikolaus Rath]

Package: systemd-container
Version: 241-5
Severity: normal
File: /usr/bin/systemd-nspawn

Not sure what to make of this:

# systemd-nspawn -M resuce --boot --private-users -D /mnt/usbdrive
Spawning container resuce on /mnt/usbdrive.
Press ^] three times within 1s to kill container.
Selected user namespace base 0 and range 65536.
Failed to register machine: Unit -.mount is masked.
Parent died too early

# systemctl status -- -.mount
● -.mount - Root Mount
   Loaded: masked (Reason: Unit -.mount is masked.)
   Active: active (mounted) since Sat 2019-09-07 09:23:09 BST; 1h 11min ago
    Where: /
     What: /dev/mapper/vg0-debian
    Tasks: 0 (limit: 4915)
   Memory: 0B
   CGroup: /system.slice/-.mount

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.


-- System Information:
Debian Release: 10.0
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-5-amd64 (SMP w/8 CPU cores)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd-container depends on:
ii  dbus             1.12.16-1
ii  libacl1          2.2.53-4
ii  libbz2-1.0       1.0.6-9.1
ii  libc6            2.28-10
ii  libcurl3-gnutls  7.64.0-4
ii  libgcrypt20      1.8.4-5
ii  liblzma5         5.2.4-1
ii  libseccomp2      2.3.3-4
ii  libselinux1      2.8-1+b1
ii  systemd          241-5
ii  zlib1g           1:1.2.11.dfsg-1

Versions of packages systemd-container recommends:
ii  btrfs-progs        4.20.1-2
pn  libnss-mymachines  <none>

systemd-container suggests no packages.

-- no debconf information