fix: "zip" Content-Type resulting in null Stream for Artifacts on Blob Storage (#2905)

Octokit.Tests/Http/HttpClientAdapterTests.cs

@@ -177,6 +177,27 @@ namespace Octokit.Tests.Http
 
                 Assert.Equal("application/json", response.ContentType);
             }
+            
+            // See #2898 for why this is necessary
+            // Non standard MIME Content-Type coming from Blob Storage when downloading artifacts
+            [Fact]
+            public async Task SetsZipContentType()
+            {
+                var memoryStream = new MemoryStream();
+                var streamContent = new StreamContent(memoryStream);
+                streamContent.Headers.TryAddWithoutValidation("Content-Type", "zip");
+                
+                var responseMessage = new HttpResponseMessage
+                {
+                    StatusCode = HttpStatusCode.OK,
+                    Content = streamContent
+                };
+                var tester = new HttpClientAdapterTester();
+
+                var response = await tester.BuildResponseTester(responseMessage);
+
+                Assert.Equal("application/zip", response.ContentType);
+            }
         }
 
         sealed class HttpClientAdapterTester : HttpClientAdapter

Octokit/Http/HttpClientAdapter.cs

@@ -81,7 +81,6 @@ namespace Octokit.Internal
                 AcceptHeaders.RawContentMediaType,
                 "application/zip" ,
                 "application/x-gzip" ,
-                "zip" , // Not a standard MIME type but see issue #2898
                 "application/octet-stream"};
 
             var content = responseMessage.Content;
@@ -169,10 +168,18 @@ namespace Octokit.Internal
 
         static string GetContentMediaType(HttpContent httpContent)
         {
-            if (httpContent.Headers != null && httpContent.Headers.ContentType != null)
+            if (httpContent.Headers?.ContentType != null)
             {
                 return httpContent.Headers.ContentType.MediaType;
             }
+
+            // Issue #2898 - Bad "zip" Content-Type coming from Blob Storage for artifacts
+            if (httpContent.Headers?.TryGetValues("Content-Type", out var contentTypeValues) == true
+                && contentTypeValues.FirstOrDefault() == "zip")
+            {
+                return "application/zip";
+            }
+            
             return null;
         }