Revert "Revert "s/_env_default/get_env/""
Revert "Revert "s/_env_default/get_env/""

Maybe this works?

This reverts commit 2970d853fa398391f2c7b1a1d12a9be25ec3c937.

jupyterhub/kubespawner,jbmarcille/kubespawner,yuvipanda/jupyterhub-kubernetes-spawner,ktong/kubespawner