Fix for SR-2913 - HTTP headers not picked up

Author: Pushkar Kulkarni

Foundation/NSURLSession/NSURLSessionTask.swift

@@ -594,7 +594,7 @@ fileprivate extension URLSessionTask {
     func curlHeaders(for request: URLRequest) -> [String] {
         var result: [String] = []
         var names = Set<String>()
-        if let hh = currentRequest?.allHTTPHeaderFields {
+        if let hh = request.allHTTPHeaderFields {
             hh.forEach {
                 let name = $0.0.lowercased()
                 guard !names.contains(name) else { return }