那些年，我踩过的坑，而后人绝不要再踩

1.

(pyenv)xluren@xluren:~/python/project$ ../pyenv/bin/pip install flask                                            Downloading/unpacking flask  Cannot fetch index base URL https://pypi.python.org/simple/  Could not find any downloads that satisfy the requirement flaskCleaning up...No distributions at all found for flaskStoring debug log for failure in /home/xluren/.pip/pip.log

引起的原因，系统时间设置