Current behavior 😯

Running repo.rev_parse_single("@{-1}") in a repo where the last checked out branch has been deleted returns the object id of the commit (tip of branch before deletion)

Expected behavior 🤔

It should return an error

Git behavior

In this case, git rev-parse --verify @{-1} returns an errors: "fatal: Needed a single revision" and exit code 128.

Steps to reproduce 🕹

Prepare a test repo (with a branch that was previously checked out but is now deleted):

git init
git commit --allow-empty -m c1
git checkout -b prev-target       
git checkout -
git branch -d prev-target

And in this repo, run repo.rev_parse_single("@{-1}") or git rev-parse --verify @{-1} previously mentioned to observe the mismatch between gix and git