Create states.py

Removed duplicate REJECTED variable

celery/states.py

@@ -142,7 +142,6 @@ REJECTED = 'REJECTED'
 #: Task is waiting for retry.
 RETRY = 'RETRY'
 IGNORED = 'IGNORED'
-REJECTED = 'REJECTED'
 
 READY_STATES = frozenset({SUCCESS, FAILURE, REVOKED})
 UNREADY_STATES = frozenset({PENDING, RECEIVED, STARTED, REJECTED, RETRY})