[stable/rabbitmq-ha] Unable to start, Read-only file system

[brianwawok]

Version of Helm and Kubernetes:
kube: GKE 1.9.4-gke.1

Client: &version.Version{SemVer:"v2.5.0", GitCommit:"012cb0ac1a1b2f888144ef5a67b8dab6c2d45be6", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.5.0", GitCommit:"012cb0ac1a1b2f888144ef5a67b8dab6c2d45be6", GitTreeState:"clean"}

Which chart:

stable/rabbitmq-ha

What happened:

Upon installing, you get hit with

sed: can't create temp file '/etc/rabbitmq/rabbitmq.confXXXXXX': Read-only file system

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

This is both an upgrade of a previously working install from kube 1.9.3, or a brand new install into kube 1.9.4

Anything else we need to know:

[brianwawok]

dupe