method header is disappears in responce when hooked

When I change the headers, it disappears from the request (SIC!)"GET / HTTP / 1.1". As a result, I can not change anything significant in a query. Also, I noticed that when I change the method or the version of the HTTP protocol - that they do not change

my code for python

from flask import Flask, request, make_response
import json
import collections
from pprint import pprint
import requests

app = Flask(__name__)

@app.route('/<param>', methods=['GET', 'POST'])
def req(param):
    #postdata = json.loads(request.data)
    postdata = json.JSONDecoder(object_pairs_hook=collections.OrderedDict).decode(request.data)

    postdata['comment'] = 'blah-blah' #correct
    postdata['highlight'] = 'red' #correct
    postdata['request']['http_version'] = 'HTTP/1.0' #never apply
    postdata['request']['headers']['User-Agent'] = 'PYTHON-requests/2.13.0' #if apply METHOD dissapear from request
    postdata['request']['headers']['sameHeader'] = 'blah-blah' #if apply METHOD dissapear from request
    postdata['request']['path'] = '/test' #never apply
    postdata['request']['method'] = u'POST' #never apply

    # postdata['request']['raw'] = postdata['request']['raw'].decode('base-64').replace('python', 'PYTHON').encode('base-64')

    response = app.response_class(
        response=json.dumps(postdata),
        status=200,
        mimetype='application/json'
    )

    return response

if __name__ == '__main__':
    app.run(port=3001, debug=True)

request before and after editing via burp buddy burpbuddy_bug

I`m using "Proxy request hook URL" method of burpbuddy

tomsteele / burpbuddy

method header is disappears in responce when hooked #30