AssertionError: Header values must be strings

[Lawouach]

Using the wsgirefserver, one gets the following exception:

Traceback (most recent call last):
File "/usr/lib/python2.7/wsgiref/handlers.py", line 85, in run
self.result = application(self.environ, self.start_response)
File "/home/plg/documents/websocks/ws4py/server/wsgiutils.py", line 153, in call
start_response("101 Switching Protocols", upgrade_headers)
File "/usr/lib/python2.7/wsgiref/handlers.py", line 178, in start_response
assert type(val) is StringType,"Header values must be strings"
AssertionError: Header values must be strings