CVE-2024-6345: setuptools vulnerable to Command Injection via package URL

The vulnerability was a command injection in the package_index module of setuptools, specifically within its download functions for VCS repositories. The analysis of the provided commit 88807c7062788254f654ea8c03427adc859321f0 shows that the methods _download_git and _download_hg within the PackageIndex class were responsible for handling git and hg repository URLs, respectively. These methods constructed shell commands using os.system and incorporated parts of the user-supplied URL (like the repository URL itself and revision identifiers) directly into these commands. This is a classic command injection pattern. The patch removed these specific methods and refactored the VCS handling into a new _download_vcs method which uses subprocess.check_call with a list of arguments, a safer alternative that prevents command injection by properly handling arguments. The _download_url method, which was a caller of _download_git and _download_hg, was also modified as part of this refactoring. The primary vulnerable functions were _download_git and _download_hg due to their direct use of os.system with unsanitized input from the URL.