Try to keep two different names in python vs npm package in build.sh
@@ -4,4 +4,4 @@ set -ex
$PYTHON -m pip install . -vv
npm pack jupyter-widget-datetime@${PKG_VERSION}
mkdir -p jupyter-widget-datetime/share/jupyter/lab/extensions/js
-cp jupyter-widget-datetime-${PKG_VERSION}.tgz jupyter-widget-datetime/share/jupyter/lab/extensions/js
+cp jupyter-widget-datetime-${PKG_VERSION}.tgz ${PREFIX}/share/jupyter/lab/extensions/js
