Python pip失败但安装了包

Question

我试图在Python virtualenv中安装scipy：

$ virtualenv venv
New python executable in venv/bin/python
Installing setuptools, pip, wheel...done.
$ source venv/bin/activate
(venv)$ pip install scipy
Collecting scipy
  Using cached scipy-0.16.1.tar.gz
Collecting numpy>=1.6.2 (from scipy)
/home/kramer65/zommel/venv/local/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:90: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
  InsecurePlatformWarning
Building wheels for collected packages: scipy
  Running setup.py bdist_wheel for scipy
  Complete output from command /home/kramer65/zommel/venv/bin/python -c "import setuptools;__file__='/tmp/pip-build-6oiqvO/scipy/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" bdist_wheel -d /tmp/tmpdmYP0Hpip-wheel-:
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/tmp/pip-build-6oiqvO/scipy/setup.py", line 253, in <module>
      setup_package()
    File "/tmp/pip-build-6oiqvO/scipy/setup.py", line 241, in setup_package
      from numpy.distutils.core import setup
  ImportError: No module named numpy.distutils.core

  ----------------------------------------
  Failed building wheel for scipy
Failed to build scipy
Installing collected packages: numpy, scipy
  Running setup.py install for scipy
Successfully installed numpy-1.10.1 scipy-0.16.1
/home/kramer65/zommel/venv/local/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:90: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
  InsecurePlatformWarning

此输出首先显示Failed to build scipy，然后显示Successfully installed numpy-1.10.1 scipy-0.16.1，我不明白。

有人知道它为什么会失败并同时成功吗？