问题
In upgrading some Python modules, I also updated my Python version to 2.7.9. Doing so, however, has broken Google App Engine, and I need to revert down to at least 2.7.8. I used MacPorts to install everything. What's the easiest way to fix this?
回答1:
I haven't tried this myself, but a quick look in the MacPorts HOWTO pages indicates that you can simply activate the old version:
# Activate the old version
sudo port activate python27 @2.7.8
You can use the command port installed python27to determine which versions are currently installed.
MacPorts keeps the old versions of ports installed, but if you for some reason don't have the original version available, the HOWTO page also describes the process for finding the correct portfile and installing the older port manually.
来源：https://stackoverflow.com/questions/27815620/downgrade-python-from-version-2-7-9-to-2-7-8