test: close otks/session databases before replacing with redis db

Same fix as patch to close sqlite session db's when using anydbm
session databases. Not sure if this left open files in the working
database directory but...

Author: rouilj

test/test_redis_session.py

@@ -57,6 +57,10 @@ def setUp(self):
             pw = ""
 
         # redefine the session db's as redis.
+        # close the existing session databases before opening new ones.
+        self.db.Session.close()
+        self.db.Otk.close()
+
         self.db.config.SESSIONDB_BACKEND = "redis"
         self.db.config.SESSIONDB_REDIS_URL = \
                     'redis://%slocalhost:6379/15?health_check_interval=2' % pw