VirtualBox: nixops under Arch tries to stop -.slice, which fails

[Denommus]

The following just happens in the first deployment, when the machine is being created.

Everything seems to run smoothly, until the step where units are restarted, when this happens:

bawebsite> closures copied successfully
webserver> perl: warning: Setting locale failed.
webserver> perl: warning: Please check that your locale settings:
webserver>      LANGUAGE = (unset),
webserver>      LC_ALL = (unset),
webserver>      LANG = "en_US.UTF-8"
webserver>     are supported and installed on your system.
webserver> perl: warning: Falling back to the standard locale ("C").
webserver> updating GRUB 2 menu...
webserver> installing the GRUB 2 boot loader on /dev/sda...
webserver> Installing for i386-pc platform.
webserver> Installation finished. No error reported.
webserver> stopping the following units: -.slice, alsa-store.service, audit.service, ip-up.target, kmod-static-nodes.service, network-local-commands.service, network-setup.service, nix-daemon.service, nix-daemon.socket, nscd.service, ntpd.service, system
.slice, systemd-modules-load.service, systemd-sysctl.service, systemd-tmpfiles-clean.timer, systemd-tmpfiles-setup-dev.service, systemd-udev-trigger.service, systemd-udevd-control.socket, systemd-udevd-kernel.socket, systemd-udevd.service, systemd-vconso
le-setup.service, virtualbox.service                                                                                                                                                                                                                         
webserver> Failed to stop -.slice: Operation refused, unit -.slice may be requested by dependency only.
webserver> See system logs and 'systemctl status -.slice' for details.
packet_write_wait: Connection to 192.168.56.107 port 22: Broken pipe
webserver> error: Traceback (most recent call last):
  File "/nix/store/c00x8z5c334xkv73qg1cvf159078h8wv-nixops-1.6/lib/python2.7/site-packages/nixops/deployment.py", line 731, in worker
    raise Exception("unable to activate new configuration")
Exception: unable to activate new configuration

error: activation of 1 of 1 machines failed (namely on ‘webserver’)

If I restart the machine, though, the configuration seems to be correctly applied and the services runs correctly. This is the configuration I'm using: https://gist.github.com/Denommus/3e88cce1ebeb7dcb8a0cc65401c8c8ca

[ip1981]

I'm suffering the same. Work around - kill VirtualBox instance, start it again, redeploy.