Empty PUT to <container>/files/<filename> responds 200

[kofalt]

--------------------
---- BEGIN HTTP ----
--------------------
PUT /api/acquisitions/599dd12e13514b003ea2354b/files/image.png HTTP/1.1
Host: docker.local.flywheel.io:8443
User-Agent: Flywheel SDK
Content-Length: 3
Authorization: [redacted]
Content-Type: application/json
Accept-Encoding: gzip

{}

--------------------
-- BEGIN RESPONSE --
--------------------
HTTP/1.1 200 OK
Transfer-Encoding: chunked
Cache-Control: no-cache
Connection: keep-alive
Content-Type: application/json; charset=utf-8
Date: Wed, 23 Aug 2017 19:10:02 GMT
Expires: Wed, 23 Aug 2017 19:10:01 GMT
Server: nginx/1.9.3
Vary: Accept-Encoding

24
{"jobs_triggered": 0, "modified": 1}
0


--------------------
----- END HTTP -----
--------------------