Did that rev actually compile and make without issue for you? I was using that module a while back and ended up commenting out the below line inorder for it to build successfully.

/* static ngx_str_t ngx_http_redis_db = ngx_string("redis_db"); */

I wasn't using different redis db's at the time and didn't look into it much. I bet pipelining with agentzh's redis2 would work just fine. I saw your post over in the parser thread, did you give that a try yet?