ah_bootstrap.py 文件源码

def get_index_dist(self):
        if not self.download:
            log.warn('Downloading {0!r} disabled.'.format(DIST_NAME))
            return None

        log.warn(
            "Downloading {0!r}; run setup.py with the --offline option to "
            "force offline installation.".format(DIST_NAME))

        try:
            dist = self._do_download()
        except Exception as e:
            if DEBUG:
                raise
            log.warn(
                'Failed to download and/or install {0!r} from {1!r}:\n'
                '{2}'.format(DIST_NAME, self.index_url, str(e)))
            dist = None

        # No need to run auto-upgrade here since we've already presumably
        # gotten the most up-to-date version from the package index
        return dist