500 Octokit connection error

https://dataexplorer.azure.com/dashboards/83ee5d57-8e86-454e-b0ee-69568a6c10e7?p-_startTime=24hours&p-_endTime=now&p-_operationId=v-e3eaea10e1ebc178cad71ab86fed3cc5#8a5bc9bb-f9b8-4876-bbfa-94046fdf0174

Pull request check failed on an Octokit 500 error 3 times in a row and the workitem was dropped.

```

{
"assembly": "Microsoft.DotNet.DarcLib, Version=42.42.42.42, Culture=neutral, PublicKeyToken=null",
"method": "Microsoft.DotNet.DarcLib.GitHubClient+d__33.MoveNext",
"level": 13,
"line": 457,
"fileName": "/src/Microsoft.DotNet.Darc/DarcLib/GitHubClient.cs"
},
```