We must always execute ASKING on the connection identified by the -ASK
response before executing the actual command because not doing so will
break the cluster specifications while redis-cluster is performing a
resharding operation.
This commit reflects the recent change from the redis unstable branch
in which the number of hash slots was increased from 4096 to 16384.
See https://github.com/antirez/redis/commit/ebd666d for reference.