Don't use default value in LimitingReader

We can't simply pass the None default on to the read operation as this
default is handled differently between different wsgi implementations.

Change-Id: I337e797b8dee3dfcf9299fe361cf197a176c8fe2
Fixes: bug 1213106

keystone/common/utils.py

@@ -290,7 +290,12 @@ class LimitingReader(object):
                 yield chunk
 
     def read(self, i=None):
-        result = self.data.read(i)
+        # NOTE(jamielennox): We can't simply provide the default to the read()
+        # call as the expected default differs between mod_wsgi and eventlet
+        if i is None:
+            result = self.data.read()
+        else:
+            result = self.data.read(i)
         self.bytes_read += len(result)
         if self.bytes_read > self.limit:
             raise exception.RequestTooLarge()