git pull won't work on detached HEAD. Added repo and tag.

Author: d-m-bailey

Makefile

@@ -89,7 +89,7 @@ simlink: check-caravel
 # Update Caravel
 .PHONY: update_caravel
 update_caravel: check-caravel
-	cd $(CARAVEL_ROOT)/ && git checkout $(CARAVEL_TAG) && git pull
+	cd $(CARAVEL_ROOT)/ && git checkout $(CARAVEL_TAG) && git pull origin $(CARAVEL_TAG)
 
 # Uninstall Caravel
 .PHONY: uninstall