Merge pull request #635 from ovidner/master

Fix #634

Author: mvantellingen

Makefile

@@ -27,6 +27,6 @@ docs:
 
 release:
 	pip install twine wheel
-	rm -rf dist/*
+	rm -rf build/* dist/*
 	python setup.py sdist bdist_wheel
 	twine upload -s dist/*