[SR-6406] Fatal error: Transfer completed, but there's no response.: file Foundation/URLSession/http/HTTPURLProtocol.swift, line 549

[swift-ci]

Previous ID	SR-6406
Radar	None
Original Reporter	p_thompson (JIRA User)
Type	Bug

Environment

Swift 4.0.2-Release on Ubuntu 16.04.3

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug, RunTimeCrash
Assignee	None
Priority	Medium

md5: bf90ed399248174c721a712a653ca69f

Issue Description:

When I open this url in a web browser, I get back a 6 byte text file with the contents "THINK\n". When I download it with a dataTask (or downloadTask), Swift gives me a fatal error instead.

Here is some code to reproduce the issue:

import Foundation

let configuration = URLSessionConfiguration.default
let session = URLSession(configuration: configuration)

// url1 works
let url1 = URL(string: "https://github.com/IBM-Swift/CArchive/raw/master/module.modulemap")!
//url2 generates a Fatal error
let url2 = URL(string: "https://store-test.blobstore.apple.com/test2/think.txt?AWSAccessKeyId=MKIAQ46TEN6NTFP8PJAP&SignatureMethod=HmacSHA1&SignatureVersion=2&Expires=64092211200&Signature=jgHl7aTtiJhkvSaRC19YaH2T2qo%3D")!

let dl_task = session.dataTask(with: url2) { (data, resp, err) in
    print(String(data: data ?? Data(), encoding: .utf8) ?? "")
}
dl_task.resume()

RunLoop.main.run()

[swift-ci]

Comment by Paul Thompson (JIRA)

This file comes with trailing headers, which might be the differentiator from other files.