-b bucket selection option is not filtering other buckets for cbhealthchecker

1. create 2 buckets, saslbucket, and default.
2. Start the front end workload.
3. When the system is in dgm state, run cbhealthchecker just for default bucket

[jenkins@centos-54-x64-302 ~]$ /opt/couchbase/bin/cbhealthchecker -c 172.23.105.23:8091 -u Administrator -p password -b default
bucket: default
node: 172.23.105.29 11210
node: 172.23.105.23 11210
node: 172.23.105.30 11210
node: 172.23.105.31 11210
node: 172.23.105.25 11210
node: 172.23.105.28 11210
node: 172.23.105.32 11210
node: 172.23.105.26 11210
................................
Traceback (most recent call last):
File "/opt/couchbase/lib/python/cbhealthchecker", line 134, in ?
main()
File "/opt/couchbase/lib/python/cbhealthchecker", line 121, in main
scale = retriever.collect_data(bucket, cluster, user, password, inputfile, statsfile, scale, opts, outputdir)
File "/opt/couchbase/lib/python/collector.py", line 316, in collect_data
self.get_ns_stats(bucketlist, server, port, user, password, bucketname, scale, opts)
File "/opt/couchbase/lib/python/collector.py", line 279, in get_ns_stats
if stats_buffer.bucket_info[bucket_name]["bucketType"] == 'memcached':
KeyError: u'saslbucket'

-b option is not working properly. When we iterate stats_buffer.bucket_info, we are still looking for sasl bucket