Fix bosh release upload script
Fix bosh release upload script

- And make shellcheck happy

Signed-off-by: An Yu <446e9838deaeb979640d56c46523b7c882d598cd@pivotal.io>

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