Makefile in twilio-ruby-5.70.0 vs Makefile in twilio-ruby-5.70.1

@@ -15,10 +15,10 @@
 authors:
 	echo "Authors\n=======\n\nA huge thanks to all of our contributors:\n\n" > AUTHORS.md
 	git log --raw | grep "^Author: " | cut -d ' ' -f2- | cut -d '<' -f1 | sed 's/^/- /' | sort | uniq >> AUTHORS.md
 
 API_DEFINITIONS_SHA=$(shell git log --oneline | grep Regenerated | head -n1 | cut -d ' ' -f 5)
-CURRENT_TAG=$(shell [[ "${GITHUB_TAG}" == *"-rc"* ]] && echo "rc" || echo "latest")
+CURRENT_TAG=$(shell expr "${GITHUB_TAG}" : ".*-rc.*" >/dev/null && echo "rc" || echo "latest")
 docker-build:
 	docker build -t twilio/twilio-ruby .
 	docker tag twilio/twilio-ruby twilio/twilio-ruby:${GITHUB_TAG}
 	docker tag twilio/twilio-ruby twilio/twilio-ruby:apidefs-${API_DEFINITIONS_SHA}
 	docker tag twilio/twilio-ruby twilio/twilio-ruby:${CURRENT_TAG}