ubuntu18.04系统下用devstack安装openstack错误？
ERROR: Cannot uninstall 'PyYAML'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
WARNING: You are using pip version 20.2.4; however, version 21.1.2 is available.
You should consider upgrading via the '/usr/bin/python3.6 -m pip install --upgrade pip' command.
使用下面的安装方式解决：
pip install --ignore-installed PyYAML