Fix unable to remove web seeds

As suggested in post [1] we don't need to assign the `ti` field anymore when fastresme
already contains the `info` dict.

[1]: https://github.com/arvidn/libtorrent/issues/3946#issuecomment-523300003

src/base/bittorrent/session.cpp

@@ -1929,6 +1929,10 @@ bool Session::addTorrent_impl(CreateTorrentParams params, const MagnetUri &magne
                 , (patchedFastresumeData.constData() + patchedFastresumeData.size())};
             p.flags |= lt::add_torrent_params::flag_use_resume_save_path;
 
+            // load from .torrent file when fastresume doesn't contain the required `info` dict
+            if (!patchedFastresumeData.contains("4:infod"))
+                p.ti = torrentInfo.nativeInfo();
+
             // Still setup the default parameters and let libtorrent handle
             // the parameter merging
             hasCompleteFastresume = false;
@@ -1936,6 +1940,10 @@ bool Session::addTorrent_impl(CreateTorrentParams params, const MagnetUri &magne
             lt::error_code ec;
             p = lt::read_resume_data(fastresumeData, ec);
 
+            // load from .torrent file when fastresume doesn't contain the required `info` dict
+            if (!p.ti->is_valid())
+                p.ti = torrentInfo.nativeInfo();
+
             // libtorrent will always apply `file_priorities` to torrents,
             // if the field is present then the fastresume is considered to
             // be correctly generated and should be complete.
@@ -1972,9 +1980,9 @@ bool Session::addTorrent_impl(CreateTorrentParams params, const MagnetUri &magne
                             static_cast<lt::download_priority_t::underlying_type>(priority));
 #endif
             });
-        }
 
-        p.ti = torrentInfo.nativeInfo();
+            p.ti = torrentInfo.nativeInfo();
+        }
     }
 
     // Common