Duplicate Content-Disposition Header on File Download

[wienczny]

When trying to download an attached file I get an error about duplicate Content-Disposition headers. Using curl I get this:

curl -v http://localhost:8025/api/v1/messages/y7BMbIFKdxn05pFmZRKNKd74z6QgScJdnKYyndNcCFQ=@mailhog.example/mime/part/2/download -o /tmp/test.pdf
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0*   Trying ::1...
* Connected to localhost (::1) port 8025 (#0)
> GET /api/v1/messages/y7BMbIFKdxn05pFmZRKNKd74z6QgScJdnKYyndNcCFQ=@mailhog.example/mime/part/2/download HTTP/1.1
> Host: localhost:8025
> User-Agent: curl/7.42.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Disposition: attachment; filename="y7BMbIFKdxn05pFmZRKNKd74z6QgScJdnKYyndNcCFQ=@mailhog.example-part-2"
< Content-Disposition: inline; filename="picklist_145000114.pdf"
< Content-Transfer-Encoding: base64
< Content-Type: application/pdf
< Date: Thu, 30 Apr 2015 13:39:23 GMT
< Transfer-Encoding: chunked
< 
{ [16057 bytes data]
100 1509k    0 1509k    0     0  20.9M      0 --:--:-- --:--:-- --:--:-- 21.0M
* Connection #0 to host localhost left intact

The returned file seems to be correct, but browsers like Chrome and Firefox don't accept it because the headers are broken ;-(