From e19765ece9bbaf93d2e1257ddb374a5afff049e9 Mon Sep 17 00:00:00 2001
From: Haacked <haacked@gmail.com>
Date: Thu, 3 Oct 2013 09:27:25 -0700
Subject: [PATCH] Do not overwrite existing Accept headers

---
 Octokit.Tests/Http/JsonHttpPipelineTests.cs | 15 ++++++++++++++-
 Octokit/Http/JsonHttpPipeline.cs            |  6 +++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Octokit.Tests/Http/JsonHttpPipelineTests.cs b/Octokit.Tests/Http/JsonHttpPipelineTests.cs
index 9f0f7b93..8b91a1ba 100644
--- a/Octokit.Tests/Http/JsonHttpPipelineTests.cs
+++ b/Octokit.Tests/Http/JsonHttpPipelineTests.cs
@@ -18,7 +18,7 @@ namespace Octokit.Tests.Http
         public class TheSerializeRequestMethod
         {
             [Fact]
-            public void SetsRequestHeader()
+            public void SetsRequestAcceptHeader()
             {
                 var request = new Request();
                 var jsonPipeline = new JsonHttpPipeline();
@@ -29,6 +29,19 @@ namespace Octokit.Tests.Http
                 Assert.Equal("application/vnd.github.v3+json; charset=utf-8", request.Headers["Accept"]);
             }
 
+            [Fact]
+            public void DoesNotChangeExistingAcceptsHeader()
+            {
+                var request = new Request();
+                request.Headers.Add("Accept", "application/vnd.github.manifold-preview; charset=utf-8");
+                var jsonPipeline = new JsonHttpPipeline();
+
+                jsonPipeline.SerializeRequest(request);
+
+                Assert.Contains("Accept", request.Headers.Keys);
+                Assert.Equal("application/vnd.github.manifold-preview; charset=utf-8", request.Headers["Accept"]);
+            }
+
             [Fact]
             public void LeavesStringBodyAlone()
             {
diff --git a/Octokit/Http/JsonHttpPipeline.cs b/Octokit/Http/JsonHttpPipeline.cs
index e42bd1b1..90d90295 100644
--- a/Octokit/Http/JsonHttpPipeline.cs
+++ b/Octokit/Http/JsonHttpPipeline.cs
@@ -25,7 +25,11 @@ namespace Octokit.Http
         {
             Ensure.ArgumentNotNull(request, "request");
 
-            request.Headers["Accept"] = "application/vnd.github.v3+json; charset=utf-8";
+            if (!request.Headers.ContainsKey("Accept"))
+            {
+                request.Headers["Accept"] = "application/vnd.github.v3+json; charset=utf-8";
+            }
+            
             if (request.Endpoint != null && request.Endpoint.ToString().Contains("releases"))
                 request.Headers["Accept"] = "application/vnd.github.manifold-preview; charset=utf-8";