How to use `git2::trace_set`?

[ArseniyZvezda]

I would like to see the logs of my calls with git2 lib. I'm trying

git2::trace_set(TraceLevel::Debug, |_, res: &str| {
    println!("Git: {}", res)
})

and then something like Repository::open(...)

but console output still empty

[extrawurst]

checkout upstream libgit2. the actually calls that will create traces are sparse, AFAIK only code that talks to remotes is actually using it.