解决python setup.py egg

在安装pycurl库时遇到了这个问题：

pip install pycurl
Collecting pycurl
  Using cached pycurl-7.45.2.tar.gz (234 kB)
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error
  × python setup.py egg_info did not run successfully.
  │ exit code: 10
  ╰─> [1 lines of output]
      Please specify --curl-dir=/path/to/built/libcurl
      [end of output]
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed
× Encountered error while generating package metadata.
╰─> See above for output.
note: This is an issue with the package mentioned above, not pip.
hint: See above for details. 

在搜索之后猜测是不是版本不匹配问题，先升级了pip包：

pip install --upgrade pip
pip install --upgrade setuptools
pip install ez_setup

再重新pip install pycurl还是不行，又尝试了以下命令：

pip install pycurl==7.43.0.5 -i "https://mirrors.bfsu.edu.cn/pypi/web/simple/"

这次可以了，成功安装pycurl库之后运行结果是这样的：

Looking in indexes: https://mirrors.bfsu.edu.cn/pypi/web/simple/
Collecting pycurl==7.43.0.5
  Downloading https://mirrors.bfsu.edu.cn/pypi/web/packages/b9/21/7b0db498334b552094dc72960fb2e528699952c953652b585f0b3dd88c79/pycurl-7.43.0.5-cp37-cp37m-win_amd64.whl (1.7 MB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 1.7/1.7 MB 504.6 kB/s eta 0:00:00
Installing collected packages: pycurl
Successfully installed pycurl-7.43.0.5