Function scan 

pub fn scan(
    objects: &Handle,
    git_dir: &Path,
    common_dir: &Path,
    hash: Kind,
    config: &Config,
    partial: bool,
) -> Result<Scan>

Scans everything reachable in the repository at git_dir / common_dir.

config decides which paths are worth reading a blob for; everything else is skipped without touching the object database.

Errors

Error::Config when the object database or the reference store cannot be opened at all — “cannot tell” must never be reported as “nothing is wrong” by the one command whose whole job is to tell.