Redis redis5.0: xreadgroup a pel entry with a deleted meassage will get wrong pel entry

xadd some message.

xadd s * a1 b1
"1582614185753-0"
xadd s * a2 b2
"1582614190079-0"
xadd s * a3 b3
"1582614193671-0"

create group

xgroup create s g 0

xreadgroup some message and not ack

XREADGROUP group g c count 1 streams s >
XREADGROUP group g c count 1 streams s >

here are two pel entry. delete the first message

xdel s 1582614185753-0

xreadgroup the first pel

XREADGROUP group g c count 1 streams s 1582614185753-0

get the result of the second pel

1) 1) "s"
   2) 1) 1) "1582614190079-0"
         2) 1) "a2"
            2) "b2"

and xreadgroup the second pel will get a empty result.

XREADGROUP group g c count 1 streams s "1582614190079-0"
1) 1) "s"
   2) (empty list or set)