net/http/httputil: Keep response headers when response ContentLength is 0.

Current code does not print any response headers from httputil.DumpResponse().

   PUT /miniocloud/new-file HTTP/1.1
   Host: s3.amazonaws.com
   User-Agent: Go-http-client/1.1
   Content-Length: 11
   Accept-Encoding: gzip

   HTTP/1.1 200 OK

With this fix we get an appropriate output for httputil.DumpResponse().

   PUT /miniocloud/new-file HTTP/1.1
   Host: s3.amazonaws.com
   User-Agent: Go-http-client/1.1
   Content-Length: 11
   Accept-Encoding: gzip

   HTTP/1.1 200 OK
   Content-Length: 0
   Date: Thu, 14 Jan 2016 03:04:42 GMT
   Etag: "3e25960a79dbc69b674cd4ec67a72c62"
   Server: AmazonS3
   X-Amz-Id-2: qnXyH6sknlovV0Myy3emFAXTNtI/sQIcu1ZXNq/6wd17K32tQ7WNGB1qb3nzCpW2DhfeZ/MbWfw=
   X-Amz-Request-Id: 8422EACB0CC492BD

Fixes #13942

Change-Id: Ida063cc3524a96170d8a837893f7c9f49b6cf98e
Reviewed-on: https://go-review.googlesource.com/18624
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/net/http/httputil/dump_test.go b/src/net/http/httputil/dump_test.go
index 46bf521723..fc884347a6 100644
--- a/src/net/http/httputil/dump_test.go
+++ b/src/net/http/httputil/dump_test.go
@@ -288,6 +288,27 @@ Transfer-Encoding: chunked
 foo
 0`,
 	},
+	{
+		res: &http.Response{
+			Status:        "200 OK",
+			StatusCode:    200,
+			Proto:         "HTTP/1.1",
+			ProtoMajor:    1,
+			ProtoMinor:    1,
+			ContentLength: 0,
+			Header: http.Header{
+				// To verify if headers are not filtered out.
+				"Foo1": []string{"Bar1"},
+				"Foo2": []string{"Bar2"},
+			},
+			Body: nil,
+		},
+		body: false, // to verify we see 0, not empty.
+		want: `HTTP/1.1 200 OK
+Foo1: Bar1
+Foo2: Bar2
+Content-Length: 0`,
+	},
 }
 
 func TestDumpResponse(t *testing.T) {