Do not send content-length header when methodRewriting is false

[playnation81]

Describe the bug

• Got version: 11.5.2
• Node.js version: 14.8.0
• OS & version: Windows 10 Pro 1909

Actual behavior

Empty body request with header[content-length > 0] was sent when got a 302(Found) response status code after submitting POST request.

Expected behavior

Send empty body request without header[content-length] when got a 302(Found) response status code after submitting POST request.

Additional Info

Content-Length (if required and present) must be the size of the body of the request.
Which was mentioned by @Giotino in #1258 (comment)_

Code to reproduce

const got = require('got');

(async () => {
  try {
    const res = await got({
      url: `http://httpstat.us/302`,
      method: 'POST',
      methodRewriting: false,
      form: { aaa: 'bbb' },
    });
  } catch (err) {
    console.log(err);
  }
})();

Temporary solution

Adding a hooks.beforeRedirect to delete the Content-Length header.

const got = require('got');

(async () => {
  try {
    const res = await got({
      url: `http://httpstat.us/302`,
      method: 'POST',
      methodRewriting: false,
      form: { aaa: 'bbb' },
      hooks: {
        beforeRedirect: [
          (options, response) => {
            options.headers['content-length'] &&
              delete options.headers['content-length'];
          },
        ],
      },
    });
  } catch (err) {
    console.log(err);
  }
})();

Checklist

• I have read the documentation.
• I have tried my code with the latest version of Node.js and Got.

[szmarczak]

A user agent SHOULD send a Content-Length in a request message when

no Transfer-Encoding is sent and the request method defines a meaning
for an enclosed payload body. For example, a Content-Length header
field is normally sent in a POST request even when the value is 0
(indicating an empty payload body).

https://tools.ietf.org/html/rfc7230#section-3.3.2

[playnation81]

Sorry, I forgot to mention that I disabled the methodRewriting option.
Which means the redirected request would be a GET request and the body has been removed.

The body is removed if you disable method rewriting.
Originally posted by @szmarczak in #1271 (comment)

A user agent SHOULD NOT send a
Content-Length header field when the request message does not contain
a payload body and the method semantics do not anticipate such a
body.

https://tools.ietf.org/html/rfc7230#section-3.3.2