Merge pull request #4891 from TomTJarosz/FixFileHandler

Make `FilesHandler.get()` a decorated coroutine. Closes #4869

Author: minrk

notebook/files/handlers.py

@@ -7,7 +7,7 @@
 import json
 from base64 import decodebytes
 
-from tornado import web
+from tornado import  gen, web
 
 from notebook.base.handlers import IPythonHandler
 from notebook.utils import maybe_future
@@ -35,6 +35,7 @@ def head(self, path):
         return self.get(path, include_body=False)
 
     @web.authenticated
+    @gen.coroutine
     def get(self, path, include_body=True):
         # /files/ requests must originate from the same site
         self.check_xsrf_cookie()