From aa79af76fc7778c3d19c473d68cfdc877f6d9b69 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Fri, 17 Jan 2014 18:22:35 +0100
Subject: [PATCH] Cluster: allow CLUSTER REPLICATE to switch master.

The code was doing checks for slaves that should be done only when the
instance is currently a master. Switching a slave from a master to
another one should just work.
---
 src/cluster.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/cluster.c b/src/cluster.c
index ee95f3759..dfc115981 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -2912,10 +2912,12 @@ void clusterCommand(redisClient *c) {
             return;
         }
 
-        /* We should have no assigned slots to accept to replicate some
-         * other node. */
-        if (server.cluster->myself->numslots != 0 ||
-            dictSize(server.db[0].dict) != 0)
+        /* If the instance is currently a master, it should have no assigned
+         * slots nor keys to accept to replicate some other node.
+         * Slaves can switch to another master without issues. */
+        if (server.cluster->myself->flags & REDIS_NODE_MASTER &&
+            (server.cluster->myself->numslots != 0 ||
+            dictSize(server.db[0].dict) != 0))
         {
             addReplyError(c,"To set a master the node must be empty and without assigned slots.");
             return;