Two Kola test failures on RHCOS AWS instances

[yuqi-zhang]

Doing -b rhcos with ami ami-0fc9356f07902b569 shows the following failures:

--- FAIL: rhcos.linux.nfs.v4 (167.07s)
        nfs.go:76: NFS server booted.
        nfs.go:81: Test file "/tmp/tmp.G04yeAUFem" created on server.
        nfs.go:118: NFS client booted.
        nfs.go:131: var-mnt.mount status is "unknown": Process exited with status 3
--- FAIL: coreos.ignition.v2.once (123.83s)
        cluster.go:117: "test ! -e /etc/ignition-ran" failed: output , status Process exited with status 1

The detailed logs can be found here: https://continuous-infra-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/view/rhcos/job/jerzhang-test-coreos-rhcos-aws-test-and-launch/6/ , under build artifacts.

[ajeddeloh]

From discussion in the Ignition bug and with @arithx, it looks like the presets file is not being evaluated. Make sure the ami has a blank /etc/machine-id by default

[yuqi-zhang]

Tests are passing with openshift/os#247, closing. Thanks for investigating!