利用letsencrypte生成证书时,create virtual environment失败

./letsencrypt-auto certonly --standalone利用letsencrypt生成证书时 ,出现下面错误提示

0 upgraded, 0 newly installed, 0 to remove and 6 not upgraded.
Creating virtual environment...
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/virtualenv.py", line 2363, in <module>
main()
File "/usr/lib/python3/dist-packages/virtualenv.py", line 719, in main
symlink=options.symlink)
File "/usr/lib/python3/dist-packages/virtualenv.py", line 988, in create_environment
download=download,
File "/usr/lib/python3/dist-packages/virtualenv.py", line 918, in install_wheel
call_subprocess(cmd, show_stdout=False, extra_env=env, stdin=SCRIPT)
File "/usr/lib/python3/dist-packages/virtualenv.py", line 812, in call_subprocess
% (cmd_desc, proc.returncode))
OSError: Command /root/.local/share/letsencrypt/bin/python - setuptools pkg_resources pip wheel failed with error code 1

解决办法:
卸载virtualenv
pip uninstall virtualenv
安装virtualenv
pip install virtualenv