file upload doesn't work in combination with DigestAuth

[DavHau]

• pulsar version:
  2.0.2
• python version:
  3.6.5
• platform:
  Linux/Ubuntu16.04

Description

when posting a file while using DigestAuth as authentication method, an empty file is uploaded instead

Expected behaviour

The file should be uploaded with its correct content

Actual behaviour

A file with no content is uploaded

Steps to reproduce

FlaskDigestAuthServer.py

from flask import Flask, flash, request, redirect
from flask_httpauth import HTTPDigestAuth

app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret key here'
auth = HTTPDigestAuth()
users = {
    "root": "root",
}

@auth.get_password
def get_pw(username):
    if username in users:
        return users.get(username)
    return None

@app.route('/', methods=['GET', 'POST'])
@auth.login_required
def upload_file():
    if request.method == 'POST':
        # check if the post request has the file part
        if 'file' not in request.files:
            flash('No file part')
            return redirect(request.url)
        file = request.files['file']
        fileContent = file.read().decode()
        if fileContent == '':
            return 'file was empty'
        else:
            return fileContent
    return '''
    <!doctype html>
    <title>Upload new File</title>
    <h1>Upload new File</h1>
    <form method=post enctype=multipart/form-data>
      <input type=file name=file>
      <input type=submit value=Upload>
    </form>
    '''

if __name__ == '__main__':
    app.run(port=1337)

TestFileUpload.py

from pulsar.apps import http
from tempfile import NamedTemporaryFile
import asyncio

async def request():
  with NamedTemporaryFile() as tmpFile:
    tmpFile.write('hello world'.encode())
    tmpFile.seek(0)
    sessions = http.HttpClient()
    resp = await sessions.post(
		    'http://127.0.0.1:1337/',
		    files={'file': tmpFile},
		    auth=http.HTTPDigestAuth('root', 'root')
    )
    print(resp.text)

asyncio.get_event_loop().run_until_complete(request())

The server responds with 'file was empty' even the file had the content 'hello world'
As soon as one comments out the '@auth.login_required' from the server and the 'auth=http.HTTPDigestAuth('root', 'root')' of the client, the file content is returned correctly
This is not an issue of Flask. I noticed this this bug while trying to upload a file to some digestAuth enabled lighttpd server