ks init fails when using $KUBECONFIG env var

[lblackstone]

I'm getting the following error when trying to run ks init ks-example:

ERROR No current context found. Make sure a kubeconfig file is present

My cluster's kubeconfig is referenced in the KUBECONFIG env var, and I can interact with the cluster via kubectl.

This appears to be a regression introduced in d252456

Here is the kubeconfig I'm using:

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: <redacted>
    server: https://<redacted>:443
  name: levi
contexts:
- context:
    cluster: levi
    user: kubelet
  name: ""
current-context: ""
kind: Config
preferences: {}
users:
- name: kubelet
  user:
    client-certificate-data: <redacted
    client-key-data: <redacted

[lblackstone]

After further investigation, looks like this is related to coreos/tectonic-installer#1906

The kubeconfig doesn't have a named context or active context set.