Fix more shellcheck...
Fix more shellcheck...

Signed-off-by: Sam Coward <f2d9ddb83d985bcf331a113cd487aeceb5e618e4@pivotal.io>

cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci