lib/command/keys.js
function rename(key, newkey, req) {
  var val = this.getKey(key);
  this.delKey(key);
  this.setKey(newkey, val);
  return OK;
}
function rename(key, newkey, req) {
  var val = this.getKey(key);
  this.delKey(key);
  this.setKey(newkey, val);
  return OK;
}
function rename ( key , newkey , req ) { var val = this . getKey ( key ) ; this . delKey ( key ) ; this . setKey ( newkey , val ) ; return OK ; }
Rename a key.

Expected that command validation has already check that the key names
do not match and that the target key does exist.
Rename a key .