RDB: clarify a condition in rdbLoadRio().

src/rdb.c

@@ -2231,8 +2231,14 @@ int rdbLoadRio(rio *rdb, int rdbflags, rdbSaveInfo *rsi) {
          * an RDB file from disk, either at startup, or when an RDB was
          * received from the master. In the latter case, the master is
          * responsible for key expiry. If we would expire keys here, the
-         * snapshot taken by the master may not be reflected on the slave. */
-        if (iAmMaster() && !(rdbflags&RDBFLAGS_AOF_PREAMBLE) && expiretime != -1 && expiretime < now) {
+         * snapshot taken by the master may not be reflected on the slave.
+         * Similarly if the RDB is the preamble of an AOF file, we want to
+         * load all the keys as they are, since the log of operations later
+         * assume to work in an exact keyspace state. */
+        if (iAmMaster() &&
+            !(rdbflags&RDBFLAGS_AOF_PREAMBLE) &&
+            expiretime != -1 && expiretime < now)
+        {
             sdsfree(key);
             decrRefCount(val);
         } else {

src/rdb.h

@@ -125,6 +125,7 @@
 #define RDBFLAGS_NONE 0
 #define RDBFLAGS_AOF_PREAMBLE (1<<0)
 #define RDBFLAGS_REPLICATION (1<<1)
+#define RDBFLAGS_ALLOW_DUP (1<<2)
 
 int rdbSaveType(rio *rdb, unsigned char type);
 int rdbLoadType(rio *rdb);