Async REST API operations don't return 'Location' header

Per the snapd REST API documentation on the wiki [1], when an async operation returns the status code 202, a 'Location' reply header should be provided that specifies the URL ( /v2/changes/{change-id-from-reply}) to be used to retrieve the operation's actual status.

This is being reported against snapd version 2.20, installed on a xenial desktop.

~$ sudo curl -D - -X POST -H "Content-Type: application/json" -d '{"action":"install"}' --unix-socket /run/snapd.socket 'http:/v2/snaps/tpm'
HTTP/1.1 202 Accepted
Content-Type: application/json
Date: Fri, 06 Jan 2017 18:36:05 GMT
Content-Length: 82

{"type":"async","status-code":202,"status":"Accepted","result":null,"change":"29"}

[1] https://github.com/snapcore/snapd/wiki/REST-API