capybara/virtualenv/lib/python2.7/site-packages/pip/req/req_set.py
def prepare_files(self, finder):
        """
        Prepare process. Create temp directories, download and/or unpack files.
        """
        # make the wheelhouse
        if self.wheel_download_dir:
            ensure_dir(self.wheel_download_dir)

        self._walk_req_to_install(
            functools.partial(self._prepare_file, finder))
def prepare_files(self, finder):
        """
        Prepare process. Create temp directories, download and/or unpack files.
        """
        # make the wheelhouse
        if self.wheel_download_dir:
            ensure_dir(self.wheel_download_dir)

        self._walk_req_to_install(
            functools.partial(self._prepare_file, finder))
Prepare process. Create temp directories, download and/or unpack files.