Live rebinding patch

[Matthew Palmer]

Hi everyone,

I've recently seen a few people trying to do things that would be a lot
easier with the ability to "live" rebind a redis instance to a new IP
address -- and, handily, we built this functionality a little while ago (for
some HA, large-scale redis work we're doing which will be released in due
course).

All it does is allow 'config set bind <IP>' and 'config set bind ""' to do
the obvious thing -- change the IP address on which Redis listens. You're
still responsible for making sure that the IP address is available, and that
you don't turn off access to your Redis instance entirely (I recommend
having all redis instances listen on sockets for control traffic).
Rebinding doesn't have any impact on existing connections; Redis will
continue to service those until the client disconnects.

Patch against 2.6.0rc3 is attached. Do with it as you will. If you can't
work out how to transparently promote slaves to masters on failure, you
suffer from a lack of imagination.

- Matt

--
When I was a kid I used to pray every night for a new bicycle. Then I
realised that the Lord doesn't work that way so I stole one and asked Him to
forgive me.
-- Emo Philips