Commit indexer is not working for repository root

I am creating Virtual File system for my application. As input I am getting file paths or directory paths. I found that app works perfectly for any paths except for root.

Technically speaking I cannot get TreeEntry for repo root directory.

            Commit commit = GetCommit(commitHash);

            // this works
            var file = commit["foo.txt"];
            var dir1 = commit["var/logs"];
            var dir2 = commit["var"];

            // this doesn't work
            ver rootDir = commit["/"]; // returns null

使用此处描述的 commit indexer 和 TreeEntry 行为，重现 commit["foo.txt"]、commit["var"] 和 commit["/"] 之间的差异。跟踪 indexer 如何解析 repository 根目录，然后验证根目录查找会返回预期的 TreeEntry，同时不会破坏文件或嵌套目录的查找。