Describe the bug
nixos/tests/flannel does not succeed.

To Reproduce
nix-build nixpkgs/nixos/tests/flannel.nix

Expected behavior
The test should pass.

Additional context
Was attempting to port the test to python, couldn't find a useful test success case with the current setup or with several variations. Not sure if flannel is just broken or the original test was bad.

Metadata

 - system: `"x86_64-linux"`
 - host os: `Linux 5.3.14, NixOS, 19.09.1471.d387c2dd552 (Loris)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3`
 - channels(root): `"nixos-19.09.1471.d387c2dd552, nixos-hardware, unstable-20.03pre203904.bb1013511e1"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module: