Fix double assignment

MediaBrowser.LocalMetadata/Parsers/BaseItemXmlParser.cs

@@ -68,7 +68,7 @@ namespace MediaBrowser.LocalMetadata.Parsers
                 IgnoreComments = true
             };
 
-            _validProviderIds = _validProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            _validProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
 
             var idInfos = ProviderManager.GetExternalIdInfos(item.Item);