Add minimal reproducing code for issue 465

From https://github.com/anacrolix/torrent/issues/465#issuecomment-774869977.

internal/cmd/issue-465/main.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/anacrolix/torrent"
+	"github.com/anacrolix/torrent/metainfo"
+)
+
+func main() {
+	if err := dlTorrents("."); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+	}
+}
+
+func dlTorrents(dir string) error {
+	conf := torrent.NewDefaultClientConfig()
+	conf.DataDir = dir
+	cl, err := torrent.NewClient(conf)
+	if err != nil {
+		return err
+	}
+	ids := []string{
+		"urlteam_2021-02-03-21-17-02",
+		"urlteam_2021-02-02-11-17-02",
+		"urlteam_2021-01-31-11-17-02",
+		"urlteam_2021-01-30-21-17-01",
+		"urlteam_2021-01-29-21-17-01",
+		"urlteam_2021-01-28-11-17-01",
+		"urlteam_2021-01-27-11-17-02",
+		"urlteam_2021-01-26-11-17-02",
+		"urlteam_2021-01-25-03-17-02",
+		"urlteam_2021-01-24-03-17-02",
+	}
+	for _, id := range ids {
+		t, err := addTorrentFromURL(cl, fmt.Sprintf("https://archive.org/download/%s/%s_archive.torrent", id, id))
+		if err != nil {
+			return err
+		}
+		t.DownloadAll()
+	}
+	if !cl.WaitAll() {
+		return errors.New("client stopped early")
+	}
+	return nil
+}
+
+func addTorrentFromURL(cl *torrent.Client, url string) (*torrent.Torrent, error) {
+	fmt.Printf("Adding torrent: %s\n", url)
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("status %s", resp.Status)
+	}
+	defer resp.Body.Close()
+	meta, err := metainfo.Load(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	return cl.AddTorrent(meta)
+}