vcs_root_api.serve_property returns 406 for valid property names

I'm trying to retrieve property values for vcs_roots like this:

vcs_root_location = root_id
scm_url = con.vcs_root_api.serve_property(vcs_root_locator,'url') # Also tried with 'username' and 'branch'

It always returns 406. Am I sending it in wrong format?

Complete stack trace:

`Traceback (most recent call last):
File "list_projects.py", line 84, in
list_root_props(root.id)
File "list_projects.py", line 60, in list_root_props
stash_url = con.vcs_root_api.serve_property(vcs_root_locator,'url')
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/api/vcs_root_api.py", line 279, in serve_property
(data) = self.__serve_property_with_http_info(vcs_root_locator, name, **kwargs) # noqa: E501
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/api/vcs_root_api.py", line 1288, in __serve_property_with_http_info
collection_formats=collection_formats)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/custom/client.py", line 69, in call_api
return super(TeamCity, self).call_api(*args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/api_client.py", line 322, in call_api
_preload_content, _request_timeout)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/api_client.py", line 153, in __call_api
_request_timeout=_request_timeout)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/api_client.py", line 351, in request
headers=headers)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/rest.py", line 244, in GET
query_params=query_params)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/dohq_teamcity/rest.py", line 232, in request
raise ApiException(http_resp=r)
dohq_teamcity.rest.ApiException: (406)
Reason:
HTTP response headers: HTTPHeaderDict({'Date': 'Fri, 30 Oct 2020 16:46:40 GMT', 'Content-Type': 'text/plain', 'Transfer-Encoding': 'chunked', 'Connection': 'keep-alive', 'Set-Cookie': 'AWSALB=sM/GgBMXEUo6F6BIHG8Z1pyDZZiVu6PbeDFTkT0nfNA3ESBIESaVVWTZraJaqs/YeEQoL5OWazF+7ljrIV9RM6gWoEq9a0/MTVANoVtjqnt3mtzsVMDzgFSULlI8; Expires=Fri, 06 Nov 2020 16:46:40 GMT; Path=/, AWSALBCORS=sM/GgBMXEUo6F6BIHG8Z1pyDZZiVu6PbeDFTkT0nfNA3ESBIESaVVWTZraJaqs/YeEQoL5OWazF+7ljrIV9RM6gWoEq9a0/MTVANoVtjqnt3mtzsVMDzgFSULlI8; Expires=Fri, 06 Nov 2020 16:46:40 GMT; Path=/; SameSite=None; Secure, TCSESSIONID=012B9FE908ECBD09A37141CFD21C870F; Path=/; Secure; HttpOnly, RememberMe=; Max-Age=0; Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=/; Secure; HttpOnly', 'Server': 'nginx', 'Content-Security-Policy': "frame-ancestors 'self'", 'TeamCity-Node-Id': 'MAIN_SERVER', 'Cache-Control': 'no-store'})
HTTP response body: Responding with error, status code: 406 (Not Acceptable).
Make sure you have supplied correct 'Accept' header.`

Start with list_projects.py line 60 and follow serve_property in vcs_root_api.py through api_client.py and rest.py. Reproduce the call with the listed property names, then inspect the Accept header handling; done means valid property requests no longer return HTTP 406.

Written by the indexing model from the issue text.