allow read from replicas in pipeline

rediscluster/client.py

@@ -442,7 +442,7 @@ def pubsub(self, **kwargs):
         """
         return ClusterPubSub(self.connection_pool, **kwargs)
 
-    def pipeline(self, transaction=None, shard_hint=None):
+    def pipeline(self, transaction=None, shard_hint=None, read_from_replicas=False):
         """
         Cluster impl:
             Pipelines do not work in cluster mode the same way they do in normal mode.
@@ -461,6 +461,7 @@ def pipeline(self, transaction=None, shard_hint=None):
             result_callbacks=self.result_callbacks,
             response_callbacks=self.response_callbacks,
             cluster_down_retry_attempts=self.cluster_down_retry_attempts,
+            read_from_replicas=read_from_replicas,
         )
 
     def transaction(self, *args, **kwargs):

rediscluster/pipeline.py

@@ -194,7 +194,7 @@ def _send_cluster_commands(self, stack, raise_on_error=True, allow_redirections=
             # refer to our internal node -> slot table that tells us where a given
             # command should route to.
             slot = self._determine_slot(*c.args)
-            node = self.connection_pool.get_node_by_slot(slot)
+            node = self.connection_pool.get_node_by_slot(slot, self.read_from_replicas)
 
             # little hack to make sure the node name is populated. probably could clean this up.
             self.connection_pool.nodes.set_node_name(node)