更改mac默认python的办法

问题：
Fatal Python error: PyThreadState_Get: no current thread

解决方法
https://stackoverflow.com/questions/15678153/homebrew-python-on-mac-os-x-10-8-fatal-python-error-pythreadstate-get-no-cu

sudo port select --list python

For my computer, it showed:

Available versions for python:
none
python25-apple
python26
python26-apple
python27 (active)
python27-apple

in which python27(by Macport) was currently active. Then,

sudo port select python python27-apple