Concurrent appends to same stream and ExpectedVersion.Any on Postgres throws WrongExpectedVersion #478

ftest "repro concurrency error" {
    let streamStore () =
        let settings =
            SqlStreamStore.PostgresStreamStoreSettings
                ("Host=localhost;Port=5432;User Id=user;Password=password;Database=db")

        settings.Schema <- "teststreamstore"

        new SqlStreamStore.PostgresStreamStore(settings)

    let appendMsg msg =
        try
            (streamStore ())
                .AppendToStream(SqlStreamStore.Streams.StreamId
                                    ("test"),
                                SqlStreamStore.Streams.ExpectedVersion.Any,
                                [| msg |])
            |> Async.AwaitTask
            with exn ->
                failtest ("should not fail: " + exn.Message)

    let message () =
        SqlStreamStore.Streams.NewStreamMessage
            (System.Guid.NewGuid (), "some-type", "{}", "{}")

    List.map (fun _ -> appendMsg (message ())) [ 0 .. 10 ]
    |> List.map Async.RunSynchronously
};