When I checked in #27741, I accidentally broke the gke-ingress and autoscaler suites, despite both of them using vendored versions of the GCE provider. The problem is I added a minor option to gce.conf, but gcfg will error out on values it doesn't understand, so the old code started erroring out on new clusters (c.f. #27821 & #27813).

It would be nice to move that file to something like proto, where not-understood values are well handled.