More prevalent than I thought in 15073e86a
See also 3588783032
which is a failed github-flakes test without "Network is Online"
(cherry picked from commit 6f0bdd9ae7)
# Conflicts:
# tests/nixos/nix-docker.nix
This should help prevent some test stalls.
By default, multi-user.target does not imply that the network is fully up.
(cherry picked from commit 15073e86a8)