[chore] fixed rule to check if repository is dirty.

Author: diasbruno

Makefile

@@ -74,7 +74,7 @@ docs: build-docs
 # Rules for build and publish
 
 check-working-tree:
-	@[[ ! -z "`git status -s`" ]] && \
+	@[ ! -z "`git status -s`" ] && \
 	echo "Stopping publish. There are change to commit or discard." && \
 	exit 1