From 0bdeb861f48b4bed269e80d9211c0ce854465a4a Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 24 Jul 2018 17:31:39 +0200
Subject: [PATCH] Example the magic +1 in migrateCommand().

Related to #5154.
---
 src/cluster.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/cluster.c b/src/cluster.c
index 19688d59..8b76d9ad 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -5226,6 +5226,10 @@ try_again:
     int socket_error = 0;
     int del_idx = 1; /* Index of the key argument for the replicated DEL op. */
 
+    /* Allocate the new argument vector that will replace the current command,
+     * to propagate the MIGRATE as a DEL command (if no COPY option was given).
+     * We allocate num_keys+1 because the additional argument is for "DEL"
+     * command name itself. */
     if (!copy) newargv = zmalloc(sizeof(robj*)*(num_keys+1));
 
     for (j = 0; j < num_keys-expired; j++) {