Possible In-memory repository regression?

So I'm trying to get my branch updated with master https://github.com/Zoxive/libgit2sharp/tree/zoxive/refdb/ which revives the pluggable RefDb backend (#1226)

I've gotten through all the compile issues rebasing it up to the latest with dotnet core, and the codegen stuff. (Took a while to figure out that I had to change all the NativeMethod funcs to use the new custom marshaler)

Anyways all compiles and stuff now.. but testing my changes im running into an error that appears to be coming straight from libgit2.

LibGit2SharpException: path cannot exist in repository

It happens when i have an in memory repository and an OdbBackend.

Heres a sample unit test that shows the problem.
https://github.com/Zoxive/libgit2sharp/commit/7957581353134c17deaa71714ffd24a0a6130c5e

I did see that libgit2 had a regression (https://github.com/libgit2/libgit2/pull/4263) @ethomson fixed.
I'm guessing its related?

Commencez par exécuter le test unitaire d’exemple du commit 7957581353134c17deaa71714ffd24a0a6130c5e avec un dépôt en mémoire et un OdbBackend. Comparez l’échec avec la pull request 4263 de libgit2 et déterminez où l’exception « path cannot exist in repository » est propagée. Le travail est terminé lorsque la reproduction réussit sans provoquer de régression dans les autres backends de dépôt.