Ignore certain scenarios so they are not counted as infra failures (#889)

* Ignore certain scenarios so they are not counted as infra failures

* Check to make sure request is not cancelled

src/Sdk/DTWebApi/WebApi/Exceptions.cs

@@ -2459,6 +2459,25 @@ namespace GitHub.DistributedTask.WebApi
         }
     }
 
+    [Serializable]
+    public class UnresolvableActionDownloadInfoException : DistributedTaskException
+    {
+        public UnresolvableActionDownloadInfoException(String message)
+            : base(message)
+        {
+        }
+
+        public UnresolvableActionDownloadInfoException(String message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        protected UnresolvableActionDownloadInfoException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+    }
+
     [Serializable]
     public sealed class FailedToResolveActionDownloadInfoException : DistributedTaskException
     {