Provide default (empty value) for PROW_JOB_ID if it's unset
This will make the library script resilient to outscripts that source library.sh with the set -o nounset
@@ -29,7 +29,7 @@ readonly KNATIVE_BUILD_RELEASE=https://storage.googleapis.com/knative-releases/b
readonly KNATIVE_EVENTING_RELEASE=https://storage.googleapis.com/knative-releases/eventing/latest/release.yaml
# Useful environment variables
-[[ -n "${PROW_JOB_ID}" ]] && IS_PROW=1 || IS_PROW=0
+[[ -n "${PROW_JOB_ID:-}" ]] && IS_PROW=1 || IS_PROW=0
readonly IS_PROW
readonly REPO_ROOT_DIR="$(git rev-parse --show-toplevel)"
