This reverts commit 712e62c260.
This commit broke NixOS containers. Systemd wouldn't detect if a container
started successfully and would kill it again after a grace period.
Additionally this prints mount errors due to already mounted filesystems
at boot.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.