Fix writing JSON on Python 2

IPython/html/services/config/handlers.py

@@ -1,82 +1,88 b''
 """Tornado handlers for frontend config storage."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 import json
 import os
 import io
 from tornado import web
 
+from IPython.utils.py3compat import PY3
 from ...base.handlers import IPythonHandler, json_errors
 
 def recursive_update(target, new):
     """Recursively update one dictionary using another.
     
     None values will delete their keys.
     """
     for k, v in new.items():
         if isinstance(v, dict):
             if k not in target:
                 target[k] = {}
             recursive_update(target[k], v)
             if not target[k]:
                 # Prune empty subdicts
                 del target[k]
 
         elif v is None:
             target.pop(k, None)
 
         else:
             target[k] = v
 
 class ConfigHandler(IPythonHandler):
     SUPPORTED_METHODS = ('GET', 'PUT', 'PATCH')
 
     def file_name(self, section_name):
         return os.path.join(self.profile_dir, 'nb_%s_config.json' % section_name)
 
     @web.authenticated
     @json_errors
     def get(self, section_name):
         self.set_header("Content-Type", 'application/json')
         filename = self.file_name(section_name)
         if os.path.isfile(filename):
             with io.open(filename, encoding='utf-8') as f:
                 self.finish(f.read())
         else:
             self.finish("{}")
 
     @web.authenticated
     @json_errors
     def put(self, section_name):
         self.get_json_body()  # Will raise 400 if content is not valid JSON
         filename = self.file_name(section_name)
         with open(filename, 'wb') as f:
             f.write(self.request.body)
         self.set_status(204)
 
     @web.authenticated
     @json_errors
     def patch(self, section_name):
         filename = self.file_name(section_name)
         if os.path.isfile(filename):
             with io.open(filename, encoding='utf-8') as f:
                 section = json.load(f)
         else:
             section = {}
 
         update = self.get_json_body()
         recursive_update(section, update)
 
-        with io.open(filename, 'w', encoding='utf-8') as f:
+        if PY3:
+            f = io.open(filename, 'w', encoding='utf-8')
+        else:
+            f = open(filename, 'wb')
+        with f:
             json.dump(section, f)
+
         self.set_status(204)
 
 
 # URL to handler mappings
 
 section_name_regex = r"(?P<section_name>\w+)"
 
 default_handlers = [
     (r"/api/config/%s" % section_name_regex, ConfigHandler),
 ]