Index.Remove with directory/pattern does not always work

The problem could be related to the commit operation but I'm not sure. If instead of repo.Index.Remove("*") you pass the filename, it is correctly removed from the Index.

Also if you commit the file using the console git client the * version starts working correctly.

For reproduction please see the following unit test:

using LibGit2Sharp;
using NUnit.Framework;
using System;
using System.IO;
using System.Linq;

namespace Tests
{
    public class LibGitTest
    {
        [Test]
        public void TestRemove()
        {
            var tempPath = Path.Combine(Path.GetTempPath(), "LibGitTest");

            if (Directory.Exists(tempPath))
            {
                DeleteDirectory(tempPath);
            }
            Directory.CreateDirectory(tempPath);

            using (var repo = new Repository(Repository.Init(tempPath)))
            {
                File.WriteAllText(Path.Combine(tempPath, "a.txt"), "some text");

                repo.Stage("*.*");
                var signature = repo.Config.BuildSignature(DateTimeOffset.Now);
                repo.Commit("Initial commit", signature, signature);

                repo.Index.Remove("*");
                // repo.Index.Remove("a.txt"); // uncomment this line to make the test pass

                var status = repo.RetrieveStatus();
                Assert.Contains("a.txt", status.Removed.Select(entry => entry.FilePath).ToArray());
            }
        }

        private static void DeleteDirectory(string tempPath)
        {
            // Some files in the .git folder are readonly, I'm not sure whether that's normal, but we need to reset the flag in order to successfully delete the directory
            Directory.EnumerateFiles(Path.Combine(tempPath), "*", SearchOption.AllDirectories)
                .ForEach(f => File.SetAttributes(f, File.GetAttributes(f) & ~FileAttributes.ReadOnly));

            Directory.Delete(tempPath, recursive: true);
        }
    }
}

Start by running the TestRemove unit test and inspect the behavior of repo.Index.Remove("*") compared with removing "a.txt" directly. Trace the index removal and subsequent RetrieveStatus() result, including whether the commit operation affects pattern matching. Done means the existing test passes with the wildcard removal and the direct filename behavior remains correct.