Python requests throws Connection Broken: ChunkedEncodingError with http.client.IncompleteRead when trying to download a file

I'm trying to download a PDF file using the requests module, the code is as below:

import requests

url = "<url of the pdf>"
r = requests.get(url, stream=True, timeout=(60, 120), headers={'Connection': 'keep-alive','User-Agent': 'Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36 Edge/12.10136'})

print(r.headers)
print(r.status_code)

try:
    with open('blah.pdf', 'wb') as f:
        for chunk in r:
            # print(chunk)
            f.write(chunk)
except Exception as e:
    print(e)

Output is given below:

{'Cache-Control': 'private', 'Transfer-Encoding': 'chunked', 'Content-Type': 'application/pdf', 'Server': 'Microsoft-IIS/7.5', 'X-AspNet-Version': '4.0.30319', 'X-Powered-By': 'ASP.NET', 'Date': 'Wed, 02 Oct 2019 05:17:11 GMT', 'Set-Cookie': 'bbb=rd102o00000000000000000000ffff978433aao80; path=/; Httponly; Secure'}
200
('Connection broken: IncompleteRead(0 bytes read, 2 more expected)', IncompleteRead(0 bytes read, 2 more expected))

Here is the full stack trace:

Traceback (most recent call last):
  File "/storage/anaconda3/lib/python3.7/site-packages/urllib3/response.py", line 425, in _error_catcher
    yield
  File "/storage/anaconda3/lib/python3.7/site-packages/urllib3/response.py", line 755, in read_chunked
    chunk = self._handle_chunk(amt)
  File "/storage/anaconda3/lib/python3.7/site-packages/urllib3/response.py", line 709, in _handle_chunk
    self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
  File "/storage/anaconda3/lib/python3.7/http/client.py", line 612, in _safe_read
    raise IncompleteRead(b''.join(s), amt)
http.client.IncompleteRead: IncompleteRead(0 bytes read, 2 more expected)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/storage/anaconda3/lib/python3.7/site-packages/requests/models.py", line 750, in generate
    for chunk in self.raw.stream(chunk_size, decode_content=True):
  File "/storage/anaconda3/lib/python3.7/site-packages/urllib3/response.py", line 560, in stream
    for line in self.read_chunked(amt, decode_content=decode_content):
  File "/storage/anaconda3/lib/python3.7/site-packages/urllib3/response.py", line 781, in read_chunked
    self._original_response.close()
  File "/storage/anaconda3/lib/python3.7/contextlib.py", line 130, in __exit__
    self.gen.throw(type, value, traceback)
  File "/storage/anaconda3/lib/python3.7/site-packages/urllib3/response.py", line 443, in _error_catcher
    raise ProtocolError("Connection broken: %r" % e, e)
urllib3.exceptions.ProtocolError: ('Connection broken: IncompleteRead(0 bytes read, 2 more expected)', IncompleteRead(0 bytes read, 2 more expected))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "test.py", line 12, in <module>
    for chunk in r:
  File "/storage/anaconda3/lib/python3.7/site-packages/requests/models.py", line 753, in generate
    raise ChunkedEncodingError(e)
requests.exceptions.ChunkedEncodingError: ('Connection broken: IncompleteRead(0 bytes read, 2 more expected)', IncompleteRead(0 bytes read, 2 more expected))

When I open that pdf on Web Browsers such as Google Chrome, chrome's builtin pdf plugin can load it properly and it is possible to read on the browser. However, If I try to download it by clicking on the download icon I get Failed - Network Error Firefox can't load/download it. (Both Firefox & Chrome are upgraded to latest version) When I test it on a windows machine Microsoft edge was able to download the pdf though...

The above code, If I test it with some other pdfs such as this one: https://adobe.com/content/dam/acom/en/accessibility/products/acrobat/pdfs/acrobat-x-accessibility-checker.pdf
It works perfectly.

I've tried some command-line tools such as curl, wget, aria2c (with proper headers set like browser request) all failed to download the pdf.

wget output:

connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [application/pdf]
Saving to: ‘blah.pdf’

<pdf_url>     [      <=>                          ] 101.68K  66.1KB/s    in 1.5s    

2019-10-02 11:29:50 (69.1 KB/s) - Read error at byte 108786 (Success).

The file downloaded using wget is corrupted.

Another thing that I've tried is to inspect it using mitm and chromedriver+selenium combination.

The automated chrome browser can't load the pdf and shows an error:

502 Bad Gateway
HttpSyntaxException('Malformed chunked body',)

How can I download this pdf using requests module? Any help will be very much appreciated.