New: Auto map known legacy BaseUrls for non-Cardigann

src/NzbDrone.Core/Indexers/Definitions/BroadcastheNet/BroadcastheNet.cs

@@ -20,6 +20,8 @@ namespace NzbDrone.Core.Indexers.BroadcastheNet
         public override TimeSpan RateLimit => TimeSpan.FromSeconds(5);
 
         public override string[] IndexerUrls => new string[] { "https://api.broadcasthe.net/" };
+        public override string[] LegacyUrls => new string[] { "http://api.broadcasthe.net/" };
+
         public override string Description => "BroadcasTheNet (BTN) is an invite-only torrent tracker focused on TV shows";
 
         public BroadcastheNet(IIndexerHttpClient httpClient, IEventAggregator eventAggregator, IIndexerStatusService indexerStatusService, IConfigService configService, Logger logger)

src/NzbDrone.Core/Indexers/Definitions/Cardigann/Cardigann.cs

@@ -126,6 +126,7 @@ namespace NzbDrone.Core.Indexers.Cardigann
                 Description = definition.Description,
                 Implementation = GetType().Name,
                 IndexerUrls = definition.Links.ToArray(),
+                LegacyUrls = definition.Legacylinks.ToArray(),
                 Settings = new CardigannSettings { DefinitionFile = definition.File },
                 Protocol = DownloadProtocol.Torrent,
                 Privacy = definition.Type switch