git下载完esp-idf后，进入esp-idf目录，执行./install.sh后，出错如下错

Collecting virtualenv
Downloading virtualenv-20.0.31-py2.py3-none-any.whl (4.9 MB)
|██▏ | 337 kB 2.2 kB/s eta 0:33:54ERROR: Exception:
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/pip/_vendor/urllib3/response.py ...