HAProxy bug with balance uri + option prefer-last-server + hash-type consistent

haproxy-sample.cfg

global
    pidfile /tmp/haproxytest.pid

defaults
    # we do web !
    mode http
    option httpchk /c
    option http-keep-alive
    option http-pretend-keepalive

listen test1
    bind 127.0.0.1:8001
    monitor-uri /c
    errorfile 503 /tmp/test1.html

listen test2
    bind 127.0.0.1:8002
    monitor-uri /c
    errorfile 503 /tmp/test2.html

listen test3
    bind 127.0.0.1:8003
    monitor-uri /c
    errorfile 503 /tmp/test3.html

listen webtest:80
    id 12
    #balance source
    hash-type consistent
    option prefer-last-server
    balance uri
    bind 127.0.0.1:8000
    maxconn 60000

    server s1 127.0.0.1:8001 weight 5 check
    server s2 127.0.0.1:8002 weight 5 check
    server s3 127.0.0.1:8003 weight 5 check

test1.html

HTTP/1.1 200 Found
Connection: keep-alive
Content-Type: text/plain

This is test1

test2.html

HTTP/1.1 200 Found
Connection: keep-alive
Content-Type: text/plain

This is test2

test3.html

HTTP/1.1 200 Found
Connection: keep-alive
Content-Type: text/plain

This is test3