Setting `content-type` creates a second entry instead of replacing default

[Nick Ramsbottom]

We are using the following configuration:

{
  "root": "_site",
  "headers": {
    "/**": {
      "Access-Control-Allow-Origin": "*",
      "Surrogate-Control": "max-age=60, stale-while-revalidate=60, stale-if-error=86400",
      "Cache-Control": "max-age=0, no-cache, must-revalidate"
    },
    "/some-path": {
      "Content-Type": "application/json"
    }
  }
}

/some-path has the following response headers:

< HTTP/1.1 200 OK
< Connection: keep-alive
< Server: nginx
< Date: Tue, 17 Sep 2019 12:57:39 GMT
< Content-Type: application/octet-stream
< Content-Length: 524
< Last-Modified: Tue, 17 Sep 2019 10:52:53 GMT
< Content-Type: application/json
< Etag: "5d80bb05-20c"
< Accept-Ranges: bytes
< Via: 1.1 vegur
<

The original content-type header is returned as well as the one we have added.

[Ed Morley]

Hi

This buildpack is now deprecated and we are recommending people move the more actively maintained heroku-buildpack-nginx. For migration advice see here.

As such, I'm closing this issue out since we won't be making further changes to this buildpack.