List of changes:
- The cluster connection can be initialized with a partial list of
nodes, the full slots map will be fetched from Redis itself using
the CLUSTER NODES command.
- The slots map can be optionally retrieved from Redis if the server
returns a -MOVE response, otherwise only the interested slot will
be permanently reassigned to the new target node.
- $cluster->connect() connects to a random connection in the pool
instead of forcing the connect operation on all the connections.
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.