Merge remote-tracking branch 'origin/master'

Author: Danie1s

Sources/TRCache.swift

@@ -291,13 +291,15 @@ extension TRCache {
     ///
     /// - Parameter task:
     public func removeTmpFile(_ task: TRDownloadTask) {
+        objc_sync_enter(self)
         ioQueue.async {
             if task.fileName.isEmpty { return }
             let path = (self.downloadTmpPath as NSString).appendingPathComponent(task.fileName)
             if self.fileManager.fileExists(atPath: path) {
                 try? self.fileManager.removeItem(atPath: path)
             }
         }
+        objc_sync_exit(self)
     }
 }