Crash when running in cibuild

[bart-degreed]

Found a crash (see here), resulting from this commit. Two causes I can think of:

1. The commit contains delete of the file ".github/CONTRIBUTING.MD" and add of the file ".github/CONTRIBUTING.md" (note the case change in file extension)
2. I did several forced pushes to the PR branch, so perhaps that made commit hashes invalid?

Note I'm using this script to run during cibuild.

Sorry for not providing clear repo steps this time, but I thought you'd like to know. Will report back if this happens more than once and I have more info.

[bart-degreed]

I've found the source of this crash, which turns out to be unrelated to ReGitLint, so I'm closing this. For details, see my comment in json-api-dotnet/JsonApiDotNetCore@110fd79:

In the past, we used $env:APPVEYOR_PULL_REQUEST_HEAD_COMMIT for the merge commit hash. That is the pinned hash at the time the build is enqueued. When a force-push happens after that, while the build hasn't yet started, this hash becomes invalid during the build, resulting in a lookup error. To prevent failing the build for unobvious reasons we use HEAD, which is always the latest version.