Stuck at Stripped prohibited headers from URLFetch request: ['Host', 'Content-Length']

[Vinay Joseph via StackOverflow]

I have written a Flask app to upload an image file. The route is as follows

@app.route('/upload', methods=['POST'])
def upload_files():
    if 'file' in request.files:
        filename = request.files['file']
        filename.save('images/uploaded.jpg')
        return 'Uploaded'
    else:
        return 'Not uploaded'

I am testing this route using the following file.

import requests

url = 'http://localhost:8080/upload'
files = {'file':open('pexels.jpg','rw')}

r = requests.post(url, files=files)
print(r.text)

When I run the test I get the following Warning and it gets stuck.

WARNING  2017-05-17 14:37:11,214 urlfetch_stub.py:534] Stripped prohibited headers from URLFetch request: ['Host', 'Content-Length']

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