Fix Monitor's next_command parsing for CLUSTER SHARDS command - issue catched by a flaky test behavior

Author: petyaslavova

redis/client.py

@@ -761,9 +761,14 @@ def next_command(self):
             client_port = client_info[5:]
             client_type = "unix"
         else:
-            # use rsplit as ipv6 addresses contain colons
-            client_address, client_port = client_info.rsplit(":", 1)
-            client_type = "tcp"
+            if client_info == "":
+                client_address = ""
+                client_port = ""
+                client_type = "unknown"
+            else:
+                # use rsplit as ipv6 addresses contain colons
+                client_address, client_port = client_info.rsplit(":", 1)
+                client_type = "tcp"
         return {
             "time": float(command_time),
             "db": int(db_id),