After pasting a Personal Access Token during auth login, the flow would error out while trying to verify that the token has correct scopes. This was because of a malformed Authorization header. GitHub.com users were not affected because the API endpoint that was contacted is public and works without Authorization.

Additionally, the workflow scope is not present in GHE versions 2.x. Since we do not know which version of GHE the user plans to authenticate to, suggest in the UI that the workflow scope is only applicable to GHE 3.x:

$ gh auth login -h ghe.io
? What is your preferred protocol for Git operations? HTTPS
? Authenticate Git with your GitHub credentials? Yes
? How would you like to authenticate GitHub CLI? Paste an authentication token
Tip: you can generate a Personal Access Token here https://ghe.io/settings/tokens
The minimum required scopes are 'repo', 'read:org', 'workflow' (GHE 3.0+).
? Paste your authentication token:

Fixes #3014
Regression from #2892