fix some redirect.

login redict to home if already loged in
/hub redirect to /hub/

jupyterhub/app.py

@@ -288,8 +288,10 @@ class JupyterHubApp(Application):
 
         self.handlers = self.add_url_prefix(self.hub_prefix, h)
 
+
         # some extra handlers, outside hub_prefix
         self.handlers.extend([
+            (r"%s" % self.hub_prefix.rstrip('/'), web.RedirectHandler, {"url": self.hub_prefix}),
             (r"(?!%s).*" % self.hub_prefix, handlers.PrefixRedirectHandler),
             (r'(.*)', handlers.Template404),
         ])

jupyterhub/handlers/login.py

@@ -34,6 +34,8 @@ class LoginHandler(BaseHandler):
             # because single-user cookie may have been cleared or incorrect
             self.set_login_cookie(self.get_current_user())
             self.redirect(next_url, permanent=False)
+        elif not next_url and self.get_current_user():
+            self.redirect(self.hub.server.base_url , permanent=False)
         else:
             username = self.get_argument('username', default='')
             self.finish(self._render(username=username))