Can't run custom slugbuilder

I'm trying to run custom slugbuilder image on my cluster, I'm following [this](https://deis.com/docs/workflow/contributing/development-environment/) doc and advices from slack. For now I'm trying plain unmodified slugbuilder code.

Steps to reproduce:

1. Env and build process:

export DEIS_REGISTRY=quay.io/
export IMAGE_PREFIX=szymon_szypulski
make deploy
Image is pushed succesfully and tagged as *cannary*.
1. `kubectl edit configmap slugbuilder-config -n deis`. I'm changing image to `quay.io/szymon_szypulski/slugbuilder:canary`, pullpolicy to `Always`.
1. I'm deleting currently running builder pod, it is recreated successfully.
1. Pushing the app, build fails.
1. `kubect describe pod -n deis` shows:

State: Terminated
Reason: Error
Exit Code: 126
1. kubectl logs pod -n deis` shows:

/usr/bin/env: bash: Permission denied

I've tried minikube and [vagrant based](https://deis.com/docs/workflow/quickstart/provider/vagrant/boot/) cluster.

I'm pretty sure I'm doing something wrong, but I'm not sure what :/ I assume, official images are built same way.