venv.py

    def venv_broken(self, *, full_check=False):
        # check if a venv is broken (eg. after a python upgrade)
        # full_check validates the #! line of each bin/ script
        logger.debug("checking venv %s", self.venv_path)

        bin_path = self.venv_path / "bin"

        for bin_name in ("python3", "pip3"):
            if not (bin_path / bin_name).exists():
                logger.debug("%s not found", bin_path / bin_name)
                return True
            p = process.run(
                [bin_path / bin_name, "--version"],
                check=False,
                capture_stdout=True,
                capture_stderr=True,
            )
            if p.returncode != 0:
                return True

        if not full_check:
            return False

        for script_filename in [
            f for f in bin_path.glob("*") if f.is_file() and is_executable(f)
        ]:
            try:
                with script_filename.open("rb") as f:
                    block = f.read(80)
                block.index(10)
                first_line = block.splitlines()[0].decode("utf8")
                if first_line.startswith("#!"):
                    executable = Path(first_line.split(" ")[0][2:])
                    if not executable.exists():
                        return True
            except (IOError, ValueError):
                pass

        return False