net/http: Response.Write has bogus Connection header after auto-ungzipped Content-Length response

[sbadame]

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?
   go version go1.6 linux/amd64
2. What operating system and processor architecture are you using (go env)?
   GOARCH="amd64"
   GOBIN=""
   GOEXE=""
   GOHOSTARCH="amd64"
   GOHOSTOS="linux"
   GOOS="linux"
   GOPATH=""
   GORACE=""
   GOROOT="/usr/lib/google-golang"
   GOTOOLDIR="/usr/lib/google-golang/pkg/tool/linux_amd64"
   GO15VENDOREXPERIMENT="1"
   CC="gcc"
   GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -gno-record-gcc-switches -fdebug-prefix-map=/tmp/go-build052263605=/tmp/go-build"
   CXX="g++"
   CGO_ENABLED="1"
3. What did you do?
   I can't use the playground because this requires localhost, which the playground doesn't support.
   https://gist.github.com/sbadame/6672153feb5a5430a0129d40b263d8e9
4. What did you expect to see?
   Either "Connection: close" or "Connection:keep-alive" and a content length. Or maybe chunk encoding?
5. What did you see instead?

http.Transport.RoundTrip response: HTTP/1.1 200 OK
Connection: close
Connection: keep-alive
Keep-Alive: timeout=7200

http.DefaultClient.Do Response: HTTP/1.1 200 OK
Connection: close
Connection: keep-alive
Keep-Alive: timeout=7200

[gopherbot]

CL https://golang.org/cl/22671 mentions this issue.

[gopherbot]

CL https://golang.org/cl/23002 mentions this issue.

[gopherbot]

CL https://golang.org/cl/23003 mentions this issue.