Use Prow env variable to detect if we run under the CI environment
@@ -147,7 +147,7 @@ trap '{ make cluster-down; }' EXIT SIGINT SIGTERM SIGSTOP
# Check if we are on a pull request in jenkins.
-export KUBEVIRT_CACHE_FROM=${ghprbTargetBranch}
+export KUBEVIRT_CACHE_FROM=${PULL_BASE_REF}
if [ -n "${KUBEVIRT_CACHE_FROM}" ]; then
make pull-cache
fi
