antirez/redis — pull request #1692 by kingsumos (2014-04-17 13:52:54+00:00)
Title: Add command option to make a slave forget the replica and become a master

Added a command option to make a Slave become a Master: 'CLUSTER REPLICATE NONE'
Today the only option to make a Slave become a Master is by using the 'CLUSTER FAILOVER' command, however a switch-over is triggered and the old Master becomes a Slave.
This is useful for changing the master/slave allocation without adding/removing nodes.