软件包与`sudo python`存在，但在运行`python`时不存在

我正在AWS上配置机器。当我在AWS公共云上（使用标准发行版的Ubuntu AMI）设置此机器时，我能够sudo pip install -r REQUIREMENTS在系统范围的python发行版中成功获取所需的所有python包（例如Flask）：

[bash]$ python -c "import flask; print flask.__file__"
/usr/local/lib/python2.7/dist-packages/flask/__init__.pyc
[bash]$ python -c "import pprint, sys; pprint.pprint(sys.path)"
['',
 '/usr/local/lib/python2.7/dist-packages/setuptools-20.2.2-py2.7.egg',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-x86_64-linux-gnu',
 '/usr/lib/python2.7/lib-tk',
 '/usr/lib/python2.7/lib-old',
 '/usr/lib/python2.7/lib-dynload',
 '/usr/local/lib/python2.7/dist-packages',
 '/usr/lib/python2.7/dist-packages']

当我sudo pip install -r REQUIREMENTS在私有Ubuntu AMI上使用相同的软件包时（无疑已经过修改以具有“更好的安全性”），这些软件包似乎安装得很好，但是当我从命令行运行python时，我得到了一个ImportError。

[bash]$ python -c "import flask; print flask.__file__"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named flask

有趣的是，使用sudo运行命令会产生我在公共AWS帐户上获得的预期结果：

[bash]$ sudo python -c "import flask; print flask.__file__"
/usr/local/lib/python2.7/dist-packages/flask/__init__.pyc

sys.path在运行时是相同的python，sudo python并且两者似乎都/usr/local/lib/python2.7/dist-packages在文件中：

[bash]$ python -c "import pprint, sys; pprint.pprint(sys.path)"
['',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-x86_64-linux-gnu',
 '/usr/lib/python2.7/lib-tk',
 '/usr/lib/python2.7/lib-old',
 '/usr/lib/python2.7/lib-dynload',
 '/usr/local/lib/python2.7/dist-packages',
 '/usr/lib/python2.7/dist-packages']
[bash]$ sudo python -c "import pprint, sys; pprint.pprint(sys.path)"
['',
 '/usr/local/lib/python2.7/dist-packages/setuptools-20.2.2-py2.7.egg',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-x86_64-linux-gnu',
 '/usr/lib/python2.7/lib-tk',
 '/usr/lib/python2.7/lib-old',
 '/usr/lib/python2.7/lib-dynload',
 '/usr/local/lib/python2.7/dist-packages',
 '/usr/lib/python2.7/dist-packages']

这里的任何建议都将受到欢迎。我以前从未见过这样的东西，而且在弄清楚此修改过的Ubuntu AMI的不同之处（可能引起问题）时遇到了麻烦。