Command Injection in pip when used with Mercurial

When installing a package from a Mercurial VCS URL, e.g. pip install hg+..., with pip prior to v23.3, the specified Mercurial revision could be used to inject arbitrary configuration options to the hg clone call (e.g. --config). Controlling the Mercurial configuration can modify how and which repository is installed. This vulnerability does not affect users who aren't installing from Mercurial.