Describe the bug

Blocking reads on Redis Cluster replica nodes (in readonly mode) always get redirected to a master node.

To reproduce

Connect to a replica node, go into a readonly mode, do a blocking read, e.g.:

127.0.0.1:6381> CONNECT 127.0.0.1 6385
127.0.0.1:6385> READONLY
OK
127.0.0.1:6385> XREAD STREAMS k 0
(nil)
127.0.0.1:6385> XREAD BLOCK 100 STREAMS k 0
-> Redirected to slot [7629] located at 127.0.0.1:6381
(nil)
127.0.0.1:6381> 

Expected behavior

According to documentation of READONLY:

When the connection is in readonly mode, the cluster will send a redirection to the client only if the operation involves keys not served by the replica's master node.

blocking reads should not get redirected to a master node.

Additional information

IIUC the clusterRedirectBlockedClientIfNeeded does not handle the case when the blocking read is on a replica node: