Fixed #9548 -- Correctly detect existence of empty sessions with cache backend.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9934 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/sessions/backends/cache.py

@@ -43,7 +43,7 @@ class SessionStore(SessionBase):
             raise CreateError
 
     def exists(self, session_key):
-        if self._cache.get(session_key):
+        if self._cache.has_key(session_key):
             return True
         return False
 

django/contrib/sessions/tests.py

@@ -182,6 +182,11 @@ False
 False
 >>> cache_session.items() == prev_data
 True
+>>> cache_session = CacheSession()
+>>> cache_session.save()
+>>> key = cache_session.session_key
+>>> cache_session.exists(key)
+True
 
 >>> Session.objects.filter(pk=cache_session.session_key).delete()
 >>> cache_session = CacheSession(cache_session.session_key)