Credential handling in 0.27.0-preview-0096 fails against VSTS/Azure

Between versions preview-0034 and preview-0096 the credential handling changed and no longer works with VSTS/Azure

Include="LibGit2Sharp" Version="0.27.0-preview-0034" - works correctly

Include="LibGit2Sharp" Version="0.27.0-preview-0096" - authentication fails

Reproduction steps

string surl = "https://testsite.visualstudio.com/testsite/_git/Test";
string un = "pat";
string pwd = "";

var credentialsProvider = new CredentialsHandler((_url, _user, _cred) =>
new UsernamePasswordCredentials
{
Username = un,
Password = pwd
}
);

var references = Repository.ListRemoteReferences(surl, credentialsProvider);

Expected behavior

Should return references

Actual behavior

preview-0096 throws "this remote has never connected" error when authentication fails.

Version of LibGit2Sharp (release number or SHA1)

0.27.0-preview-0096

Operating system(s) tested; .NET runtime tested

OSx, .net core 5.0

Start by reproducing the issue with LibGit2Sharp 0.27.0-preview-0034 and preview-0096 using Repository.ListRemoteReferences, the VSTS/Azure URL, and the provided CredentialsHandler. Compare credential handling between the two versions; done means the preview-0096 case authenticates successfully and returns references instead of throwing "this remote has never connected."