/1/metadata requests returning 400 error for difficult file name

The integration tests for rclone ( http://rclone.org ) have started failing for Dropbox.  I haven't changed my code so I suspect something has changed at Dropbox.

This shows up as a failed metadata request which returns a 400 error with no explanation in the body.

I'm deliberately testing a "difficult" file name here `hello? sausage/êé/Hello, 世界/ " ' @ < > & ?/z.txt`.

I suspect my "difficult" file name might be confusing something.

2016/04/24 10:52:08 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2016/04/24 10:52:08 HTTP REQUEST
2016/04/24 10:52:08 GET /1/metadata%2Fauto%2Frclone-test-yeyazis5kuqixus0cewejez0%2Fhello%3F%20sausage%2F%C3%AA%C3%A9%2FHello%2C%20%E4%B8%96%E7%95%8C%2F%20%22%20%27%20%40%20%3C%20%3E%20%26%20%3F%2Fz.txt?file_limit=10000&include_deleted=false&list=false&locale=en HTTP/1.1
Host: api.dropbox.com
User-Agent: Go-http-client/1.1
Authorization: Bearer XXX
Accept-Encoding: gzip

2016/04/24 10:52:08 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2016/04/24 10:52:08 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
2016/04/24 10:52:08 HTTP RESPONSE
2016/04/24 10:52:08 HTTP/1.1 400 Bad Request
Connection: keep-alive
Content-Type: text/plain; charset=utf-8
Date: Sun, 24 Apr 2016 09:52:08 GMT
Server: nginx
X-Dropbox-Request-Id: d8bc2d70a3069accc781556808d9dca0
Content-Length: 0

2016/04/24 10:52:08 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
2016/04/24 10:52:08 hello? sausage/êé/Hello, 世界/ " ' @ < > & ?/z.txt: Error reading file: unexpected HTTP status code 400