Enforce correct playback order after playlist reload

[iSerganov]

Hey community!

I am trying to workaround the issue mentioned here: #4316.

I have some progress, but still cant get it work.

The problem occurs in the following scenario:

1. Liquidsoap plays some playlist.pls with tracks a, b, and c
2. Let's say playlist.pls is reloaded while playing track b
3. New version of playlist.pls contains tracks d, e, f and g
4. After finishing the playback of b track Liquidsoap does request queuing in reverse order.
5. Request queue looks like this: f, e, d (provided we have prefetch_request set to 3)
6. As the result the playback also starts in the reverse order.
7. This happens only while the very first queuing - after it the order is correct.

So I am trying to workaround it by the following on_reload callback, simplified code can be found below:

myplaylist = playlist("/playlist.pls",reload_mode="watch",mode="normal", on_reload=chk_source_order)

...

def chk_source_order() =
    # currently queue looks as follows: `f`, `e`, `d`
    # reverse the queue and resolve outstanding requests in reversed order
    q = list.map.right(fun (req) -> 
              begin
                print("request status: #{request.status(req)}, request metadata: #{request.metadata(req)}")
                ignore(request.destroy(req))
                request.create(request.uri(req))
              end, myplaylist.queue())
   # New requests order is correct now: `d`, `e`, `f`
   # My assumption was that if I recreate requests and put them in reversed order back to the playlist's queue
   # they will be played in a good order,
   # but in fact they are simply skipped and playback proceeds with the following song (`g`)
   myplaylist.set_queue(q)
end

My question is how to enforce correct playback order of the first queue requests after playlist reload?