Restored 2.5 compatibility and actual fix for the json problem

.gitignore

@@ -2,6 +2,8 @@
 *.pyc
 *.pyo
 env
+env*
 dist
+*.egg
 *.egg-info
 _mailinglist

flask/helpers.py

@@ -19,6 +19,7 @@ from zlib import adler32
 # try to load the best simplejson implementation available.  If JSON
 # is not installed, we add a failing class.
 json_available = True
+json = None
 try:
     import simplejson as json
 except ImportError:
@@ -32,7 +33,6 @@ from werkzeug import Headers, wrap_file, is_resource_modified, cached_property
 from jinja2 import FileSystemLoader
 
 from .globals import session, _request_ctx_stack, current_app, request
-from .wrappers import Response
 
 
 def _assert_have_json():
@@ -364,3 +364,7 @@ class _PackageBoundObject(object):
                          subfolders use forward slashes as separator.
         """
         return open(os.path.join(self.root_path, resource), 'rb')
+
+
+# circular dependencies between wrappers and helpers
+from .wrappers import Response

flask/module.py

@@ -9,7 +9,7 @@
     :license: BSD, see LICENSE for more details.
 """
 
-from flask.helpers import _PackageBoundObject
+from .helpers import _PackageBoundObject
 
 
 def _register_module(module, static_path):

flask/wrappers.py

@@ -12,7 +12,7 @@
 from werkzeug import Request as RequestBase, Response as ResponseBase, \
     cached_property
 
-from .helpers import json
+from .helpers import json, _assert_have_json
 
 
 class Request(RequestBase):
@@ -52,7 +52,6 @@ class Request(RequestBase):
         parsed JSON data.
         """
         if __debug__:
-            from flask.helpers import _assert_have_json
             _assert_have_json()
         if self.mimetype == 'application/json':
             return json.loads(self.data)