Hi,  When we are attempting to get a new access_token using a refresh_token on test.salesforce.com 

https://test.salesforce.com/services/oauth2/token?grant_type=refresh_token&client_id=3....JFK&refresh_token=5....X==

salesforce is returning a return code of 200, but there are 2 Transfer-Encoding Fields with the value of 'chunked' in the response Header

This seems to be out of compliance with http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.6

Which states

Whenever a transfer-coding is applied to a message-body, the set of transfer-codings MUST include "chunked", unless the message is terminated by closing the connection. When the "chunked" transfer- coding is used, it MUST be the last transfer-coding applied to the message-body. The "chunked" transfer-coding MUST NOT be applied more than once to a message-body. These rules allow the recipient to determine the transfer-length of the message

This behavior is not occuring on our login.salesforce.com instance, and I just noticed that it started happening on Tuesday when my Web client started to reject the double chunked response headers.