Fix parent-release-branch

Author: danudey

lib.Makefile

@@ -645,7 +645,7 @@ REPO_DIR=$(shell if [ -e hack/format-changed-files.sh ]; then echo '.'; else ech
 fix-changed go-fmt-changed goimports-changed:
 	$(DOCKER_RUN) -e release_prefix=$(RELEASE_BRANCH_PREFIX)-v \
 	              -e git_repo_slug=$(GIT_REPO_SLUG) \
-	              -e parent_branch=$(shell $(REPO_ROOT)/hack/find-parent-release-branch.sh) \
+	              -e parent_branch=$(shell $(REPO_DIR)/hack/find-parent-release-branch.sh) \
 	              $(CALICO_BUILD) $(REPO_DIR)/hack/format-changed-files.sh
 
 .PHONY: fix-all go-fmt-all goimports-all