Fixed: Ignore IOException deleting download folder after import

(cherry picked from commit d05cb40088a51eef5a2830bf2b55f5d05955578f)

src/NzbDrone.Core/MediaFiles/DownloadedBooksImportService.cs

@@ -231,7 +231,15 @@ namespace NzbDrone.Core.MediaFiles
                 ShouldDeleteFolder(directoryInfo))
             {
                 _logger.Debug("Deleting folder after importing valid files");
-                _diskProvider.DeleteFolder(directoryInfo.FullName, true);
+
+                try
+                {
+                    _diskProvider.DeleteFolder(directoryInfo.FullName, true);
+                }
+                catch (IOException e)
+                {
+                    _logger.Debug(e, "Unable to delete folder after importing: {0}", e.Message);
+                }
             }
 
             return importResults;