git-llvm-push: Error 422: Unprocessable Entity

I got the following error:
```
Creating pull request for 'nikic:users/nikic/arm-generate-test-checks-nfc-1'...
Pull request created: https://github.com/llvm/llvm-project/pull/184574
Setting labels for #184574: skip-precommit-approval
Error making API request to https://api.github.com/repos/llvm/llvm-project/issues/184574/labels: HTTP Error 422: Unprocessable Entity
Returning to original branch: main
Cleaning up temporary remote branches...
Error making API request to https://api.github.com/repos/llvm/llvm-project/git/refs/heads/users/nikic/arm-generate-test-checks-nfc-1: HTTP Error 422: Unprocessable Entity
```
Both setting the label and performing the merge failed and had to be done manually.