update-common:
	@mkdir -p $(TMP)
	@git clone -q --depth 1 --single-branch --branch $(UPDATE_BRANCH) https://github.com/$(BUILD_TOOLS_ORG)/common-files $(TMP)/common-files
	@cd $(TMP)/common-files ; git rev-parse HEAD >files/common/.commonfiles.sha
	@rm -fr common
# istio/community has its own CONTRIBUTING.md file.
	@CONTRIB_OVERRIDE=$(shell grep -l "istio/community/blob/master/CONTRIBUTING.md" CONTRIBUTING.md)
	@if [ "$(CONTRIB_OVERRIDE)" != "CONTRIBUTING.md" ]; then\