Prefetch-metadata fails on GTKUI thin-client.

[mhertz]

When selecting to add a magnet in GTKUI, then prefetching metadata(files) works in classic-mode, but fails in thinclient-mode, and just tries continually without resolving, though you can select to add the magnet anyways.

Here's relevant snippets of two logs of adding an arch-linux iso magnet, first in classic and next in failed thin-client mode.

Classic-mode:

18:13:58 [DEBUG   ][deluge.core.alertmanager          :135 ] Handling alert: session_stats_alert
18:13:58 [DEBUG   ][deluge.ui.gtk3.toolbar            :105 ] on_toolbutton_add_clicked
[...]
18:14:02 [DEBUG   ][deluge.core.alertmanager          :135 ] Handling alert: state_changed_alert
18:14:02 [DEBUG   ][deluge.core.alertmanager          :130 ] torrent_checked_alert: archlinux-2019.10.01-x86_64.iso checked
18:14:02 [DEBUG   ][deluge.core.alertmanager          :135 ] Handling alert: torrent_checked_alert
18:14:02 [DEBUG   ][deluge.core.torrentmanager        :388 ] remove prefetch magnet from session
18:14:02 [DEBUG   ][deluge.core.torrentmanager        :398 ] prefetch metadata received
18:14:02 [DEBUG   ][deluge.ui.gtk3.addtorrentdialog   :269 ] magnet metadata for magnet:?xt=urn:btih:4ebd3250ac87a5296d7c9738b8388cb6e2b44429&dn=archlinux-2019.10.01-x86_64.iso&tr=udp://tracker.archlinux.org:6969&tr=http://tracker.archlinux.org:6969/announce (4ebd3250ac87a5296d7c9738b8388cb6e2b44429)

Thinclient-mode:

18:06:17 [DEBUG   ][deluge_execute.gtkui              :84  ] Adding command `02117af8932d5721dddd4e4b6ecbcd34c8766b49`
18:06:26 [DEBUG   ][deluge.ui.gtk3.gtkui              :298 ] RPC: Sent 3.0 KiB (0.0 KiB/s) Recv 6.9 KiB (0.0 KiB/s)
18:06:27 [DEBUG   ][deluge.ui.gtk3.toolbar            :105 ] on_toolbutton_add_clicked
18:06:27 [DEBUG   ][deluge.ui.gtk3.menubar            :248 ] on_menuitem_addtorrent_activate
18:06:30 [DEBUG   ][deluge.ui.gtk3.addtorrentdialog   :744 ] on_button_url_clicked
18:06:31 [DEBUG   ][deluge.ui.gtk3.addtorrentdialog   :769 ] url: magnet:?xt=urn:btih:4ebd3250ac87a5296d7c9738b8388cb6e2b44429&dn=archlinux-2019.10.01-x86_64.iso&tr=udp://tracker.archlinux.org:6969&tr=http://tracker.archlinux.org:6969/announce
18:06:32 [WARNING ][deluge.transfer                   :136 ] Failed to decompress (24643 bytes) and load serialized data with rencode: 'utf-8' codec can't decode byte 0xb4 in position 0: invalid start byte
18:06:36 [DEBUG   ][deluge.ui.gtk3.gtkui              :298 ] RPC: Sent 4.2 KiB (0.1 KiB/s) Recv 31.9 KiB (2.5 KiB/s)
18:06:45 [DEBUG   ][deluge.ui.gtk3.addtorrentdialog   :883 ] on_button_cancel_clicked
18:06:46 [DEBUG   ][deluge.ui.gtk3.gtkui              :298 ] RPC: Sent 5.1 KiB (0.1 KiB/s) Recv 32.7 KiB (0.1 KiB/s)
18:06:49 [DEBUG   ][deluge.ui.gtk3.menubar            :258 ] on_menuitem_quitdaemon_activate

Thanks in advance.