Test RDB merge on load with active replication

Former-commit-id: 28183f4b66fc4c865048080b61e599eeb1d2293b

tests/integration/replication-active.tcl

@@ -223,6 +223,30 @@ start_server {tags {"active-repl"} overrides {active-replica yes}} {
     
     exec kill -SIGCONT $slave_pid
 
+    test {Active replica merge works when reconnecting} {
+        $slave flushall
+        $slave set testkey foo
+        wait_for_condition 50 1000 {
+            [string match *foo* [$master get testkey]]
+        } else {
+            fail "Replication failed to propogate"
+        }
+        $slave replicaof no one
+        $master replicaof no one
+        after 100
+        $master set testkey baz
+        after 100
+        $slave set testkey bar
+        after 100
+        $slave replicaof $master_host $master_port
+        after 1000
+        $master replicaof $slave_host $slave_port
+        after 1000
+
+        assert_equal {bar} [$slave get testkey]
+        assert_equal {bar} [$master get testkey]
+    }
+
     test {Active replica different databases} {
         $master select 3
         $master set testkey abcd