Ensure.HandleError does not set GitErrorCategory.

Reproduction steps

This reproduces with any error handled by Ensure.HandleError, but my exact repro steps are:

1. Clone repository
2. Commit
3. Push with credentials that have only read permissions to the repo.

Looking at the error message, the error appears to be thrown from here.

Expected behavior

Exception is thrown and the ex.Data["libgit2.category"] is set to a proper value. In my case it would be GitErrorCategory.Net.

Actual behavior

Exception is thrown, but the ex.Data["libgit2.category"] has value -1.

Version of LibGit2Sharp (release number or SHA1)

0.26.2

Operating system(s) tested; .NET runtime tested

Windows 10 1909; NET 4.6.1

LibGit2Sharp/Core/Ensure.cs の Ensure.HandleError から始め、libgit2 の src/transports/winhttp.c に記載されているネイティブエラーパスと比較します。Windows で読み取り専用の push を再現し、ex.Data["libgit2.category"] がどのように割り当てられるかを調べます。このパスが -1 ではなく GitErrorCategory.Net を報告すれば完了です。