Ensure jsx is in sdist

MANIFEST.in

@@ -8,6 +8,7 @@ include *requirements.txt
 include Dockerfile
 
 graft onbuild
+graft jsx
 graft jupyterhub
 graft scripts
 graft share
@@ -18,6 +19,10 @@ graft ci
 graft docs
 prune docs/node_modules
 
+# Intermediate javascript files
+prune jsx/node_modules
+prune jsx/build
+
 # prune some large unused files from components
 prune share/jupyterhub/static/components/bootstrap/dist/css
 exclude share/jupyterhub/static/components/bootstrap/dist/fonts/*.svg

setup.py

@@ -278,8 +278,6 @@ class JSX(BaseCommand):
             return True
 
         js_target_mtime = mtime(self.js_target)
-        # The sdist doesn't contain the jsx directory so this always returns 0
-        # if run from the dist/*.tar.gz
         jsx_mtime = recursive_mtime(self.jsx_dir)
         if js_target_mtime < jsx_mtime:
             return True