Get key in view result failing with 401 for blank password in CBSV5.0

We are using python SDK 2.2.5 for view query . When we provide password other than blank password for bucket, script works fine. but when we set blank password for bucket and try to query view with blank password, we are getting below error

cluster = Cluster('couchbase://

'.format(CBSFQDN))
cluster.authenticate(PasswordAuthenticator('ptxdata',''))
CB = cluster.open_bucket('ptxdata')
try:
QueryOut = CB.query(Design, Name, query=QueryStr)
except CouchbaseError as e:
log.error('Error:' + str(e) + '')
sys.exit(1)
try:
for row in QueryOut:
print row.key
DocIDArray.append(row.key)
except Exception, e:
log.error('Error:' + str(e) + '',exc_info=True)

LogOutPut:

12-27-2017 23:40:20.439 [ERROR][MainThread] - [SYNCPurgeDelDocBlobs] -[GetDocIDList] - Error:<RC=0x3B[HTTP Operation failed. Inspect status code for details], HTTP Request failed. Examine 'objextra' for full result, Results=1, C Source=(src/http.c,140), OBJ=ViewResult<rc=0x3B[HTTP Operation failed. Inspect status code for details], value=None, http_status=401>>
Traceback (most recent call last):
File "SYNCPurgeDelDocBlobs.py", line 291, in GetDocIDList
for row in QueryOut:
File "/DG/activeRelease/lib/python_lib/couchbase/views/iterator.py", line 399, in _iter_
raw_rows = self.raw.fetch(self._mres)
HTTPError: <RC=0x3B[HTTP Operation failed. Inspect status code for details], HTTP Request failed. Examine 'objextra' for full result, Results=1, C Source=(src/http.c,140), OBJ=ViewResult<rc=0x3B[HTTP Operation failed. Inspect status code for details], value=None, http_status=401>>