fixed incorrect content-length on digest authentication request. (#28…

[liefersfl]

…65 #2954 #2777)

PR Checklist:

• I have run npm test locally and all tests are passing.
• I have added/updated tests for any new behavior.
  
• If this is a significant change, an issue has already been created where the problem / solution was discussed: [N/A, or add link to issue here]
  

PR Description

There was a bug in handling requests with two step authentication (eg. digest) and formdata. In the first step, the content-length of the formdata was calculated and sent in the request header as "content-length: xxx" but the content was not sent. The whole request ended in a timeout while the server was waiting for the content.

The following example produces a timeout:

const options = {
   method: "POST",
   url: "<url to server>",
   auth: {
       user: 'abcde0ab963dc088cca337e19ebb6e95',
       pass: 'abcde1f223f4200e5b74273a1538ecc8752ddde93d6c8e45c50e55c9392a11ec',
       sendImmediately: false
     }
}

var r = request(options, function(err, httpResponse, body) {
   if (err) {
       console.log(err)
   }
   console.log("Done")
})

var form = r.form();
form.append('file', fs.createReadStream("/tmp/test.gz"), {
   filename: 'test.gz'
})

The fix sends a zero content-length when no content will be sent.

All tests passed, i just had to create new server certificates since they expired today ;-).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.