DN's of format "cn=Last, First, cn=users, dc=test, dc=com" break with sync_groups_on_login

Similar to HUE-1428:

Having a DN of the format:

"cn=Last, First, cn=users, dc=test, dc=com"

Breaks sync_groups_on_login with:

[29/Jun/2015 11:13:38 +0000] middleware INFO Processing exception:

{'desc': 'Bad search filter'}

: Traceback (most recent call last):
File "/opt/cloudera/parcels/CDH-5.4.0-1.cdh5.4.0.p825.489/lib/hue/build/env/lib/python2.6/site-packages/Django-1.6.10-py2.6.egg/django/core/handlers/base.py", line 112, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/opt/cloudera/parcels/CDH-5.4.0-1.cdh5.4.0.p825.489/lib/hue/build/env/lib/python2.6/site-packages/Django-1.6.10-py2.6.egg/django/db/transaction.py", line 371, in inner
return func(*args, **kwargs)

Because of a bad filter:

• • • ldaps://w2k8-ad2.ad2.test.com:3269 - SimpleLDAPObject.search_ext (('dc=ad2,dc=test,dc=com', 2, '(&(&(&(objectClass=group)(|(sAMAccountName=app_dev_hue)(sAMAccountName=app_dev_hue_admin)))(|(member=tuser6)(member=CN=Test
      , User6,CN=Users,DC=ad2,DC=test,DC=com)))(cn=*))', ['objectClass', 'dn', 'memberUid', 'member', 'cn'], 0, None, None, -1, 0),{})
      File "/usr/lib64/python2.6/threading.py", line 504, in __bootstrap
      self.__bootstrap_inner()
      File "/usr/lib64/python2.6/threading.py", line 532, in __bootstrap_inner