Code review comment for ~oddbloke/cloud-init/+git/cloud-init:clean

I manually applied your change to test_clean and it does trip the check that seed_dir is not removed.

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FAIL: cloudinit.cmd.tests.test_clean.TestClean.test_remove_artifacts_removes_artifacts_skipping_seed
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Traceback (most recent call last):
  File "/home/rharper/work/git/cloud-init/cloudinit/cmd/tests/test_clean.py", line 99, in test_remove_artifacts_removes_artifacts_skipping_seed
    'Missing {0} dir'.format(expected_dir))
AssertionError: False is not true : Missing /tmp/ci-TestClean.f5keq5q_/artifacts/seed dir
-------------------- >> begin captured logging << --------------------
cloudinit.util: DEBUG: Testing if a link exists for /tmp/ci-TestClean.f5keq5q_/artifacts/seed
cloudinit.util: DEBUG: Recursively deleting /tmp/ci-TestClean.f5keq5q_/artifacts/seed
cloudinit.util: DEBUG: Testing if a link exists for /tmp/ci-TestClean.f5keq5q_/artifacts/dir2
cloudinit.util: DEBUG: Recursively deleting /tmp/ci-TestClean.f5keq5q_/artifacts/dir2
cloudinit.util: DEBUG: Testing if a link exists for /tmp/ci-TestClean.f5keq5q_/artifacts/dir1
cloudinit.util: DEBUG: Recursively deleting /tmp/ci-TestClean.f5keq5q_/artifacts/dir1
--------------------- >> end captured logging << ---------------------

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Ran 8 tests in 0.012s

Approved if CI says yes as well.