为什么IPython在系统路径？

Question

当我在IPython中打印sys.path时，我惊讶地看到在第二个位置（sys.path[1]）插入了python安装的bin。你知道吗

~> /opt/local/bin/ipython -c "import sys; [print(p) for p in sys.path]"

/opt/local/Library/Frameworks/Python.framework/Versions/3.4/bin
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python34.zip
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/plat-darwin
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/lib-dynload
/Users/kenter/Library/Python/3.4/lib/python/site-packages
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/IPython/extensions
/Users/kenter/.ipython
Out[1]: [None, None, None, None, None, None, None, None, None, None]

我指的是/opt/local/Library/Frameworks/Python.framework/Versions/3.4/bin目录。当我使用常规python打印它时，它不存在。你知道吗

~> /opt/local/bin/python -c "import sys; [print(p) for p in sys.path]"

/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python34.zip
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/plat-darwin
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/lib-dynload
/Users/kenter/Library/Python/3.4/lib/python/site-packages
/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages

那么，为什么IPython要将bin目录添加到sys.path？这样做的目的是什么？你知道吗

对我来说没什么问题，我只是好奇。你知道吗