Error in Task superset.sql_lab.get_sql_results

[febinsathar]

I was trying to use sql lab with celery its throwing me this error

[2017-02-14 04:48:55,222: ERROR/PoolWorker-1] Task superset.sql_lab.get_sql_results[b1e0bc50-1bda-4a53-a702-3dbd926afeea] raised unexpected: TypeError("a bytes-like object is required, not 'str'",)
Traceback (most recent call last):
File "/root/anaconda3/lib/python3.6/site-packages/celery/app/trace.py", line 367, in trace_task
R = retval = fun(*args, **kwargs)
File "/root/anaconda3/lib/python3.6/site-packages/celery/app/trace.py", line 622, in protected_call
return self.run(*args, **kwargs)
File "/root/anaconda3/lib/python3.6/site-packages/superset/sql_lab.py", line 156, in get_sql_results
results_backend.set(key, zlib.compress(payload))
TypeError: a bytes-like object is required, not 'str'

Superset version 0.15.4

Steps to reproduce

Am using redis as my celery broker
redshift is my database

my config file

from werkzeug.contrib.cache import FileSystemCache
RESULTS_BACKEND = FileSystemCache('/tmp/sqllab_cache', default_timeout=60247)
class CeleryConfig(object):
BROKER_URL = 'redis://localhost:6379/0'
CELERY_IMPORTS = ('superset.sql_lab', )
CELERY_RESULT_BACKEND = 'redis://localhost:6379/0'
CELERY_ANNOTATIONS = {'tasks.add': {'rate_limit': '10/s'}}
CELERY_CONFIG = CeleryConfig

[xrmx]

I think this is #2034