Downloading *.gz zipped file with python requests

I use this code (it is only a part) to download *.gz archive.

with requests.session() as s:
    s.post(login_to_site_URL, payload)    
    load = s.get(scene, stream=True)

    with open(path_to_file, "wb") as save_command:
        for chunk in load.iter_content(chunk_size=1024, decode_unicode=False):
            if chunk:
                save_command.write(chunk)
                save_command.flush()

After download the size of the file is twice more than when I download file by clicking "save as" on it. And the file is corrupted. Link for the file is:http://www.zsrcpod.aviales.ru/modistlm/archive/tlm/geo/00000/28325/terra_77835_20140806_060059.geo.hdf.gz

File require login and password, so I add a screenshot of what I see when I follow the link: http://i.stack.imgur.com/DGqtS.jpg

Looks like some options set to define this archive as a text.

file.header is:

{'content-length': '58277138',
'content-encoding': 'gzip',
'set-cookie': 'cidaviales=53616c7465645f5fc8f0abdb26f7b0536784ae4e8b302410a288f1f67ccc0afd13ce067d97ba237dc27749d9957f30457f1a1d9763b03637; path=/,
 avialestime=1407386483; path=/; expires=Wed,
 05-Nov-2014 04:41:23 GMT,
ciddaviales=53616c7465645f5fc8f0abdb26f7b0536784ae4e8b302410a288f1f67ccc0afd13ce067d97ba237dc27749d9957f30457f1a1d9763b03637; domain=aviales.ru; path=/',
'accept-ranges': 'bytes',
'server': 'Apache/1.3.37 (Unix) mod_perl/1.30',
'last-modified': 'Wed, 06 Aug 2014 06:17:14 GMT',
'etag': '"21d4e63-3793d12-53e1c86a"',
'date': 'Thu, 07 Aug 2014 04:41:23 GMT',
'content-type': 'text/plain; charset=windows-1251'}

How to properly download this file using python requests library?

It looks like requests automatically decompresses the content for you. See here

Requests automatically decompresses gzip-encoded responses, and does its best to decode response content to unicode when possible. You can get direct access to the raw response (and even the socket), if needed as well

This is default behaviour if Accept-Encoding request header contains gzip. You can check this by printing s.request.headers. To be able to get raw data you should modify this headers dict to exclude gzip, however in your case the decompressed data looks like valid hdf file - so, just save it with this extension and use it!