GHSA-FX3J-RWGX-FR94 GitPython: separate_git_dir leaks env vars via crafted .gitmodules submodule name

Summary Repo.clone's handling of separategitdir never disables Git.polishurl's environment-variable expansion, unlike every other caller of that helper that handles attacker-influenced data. Since separategitdir can be derived from an attacker-controlled .gitmodules submodule name, a completely...