使用pip安装Google App Engine时出错

Collecting google_appengine
  Downloading google-appengine-1.5.1.tar.gz (897kB)
    100% |████████████████████████████████| 901kB 1.9MB/s 
    Complete output from command python setup.py egg_info:
    Downloading http://pypi.python.org/packages/source/d/distribute/distribute-0.6.14.tar.gz
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/private/var/folders/88/5jq5gz011sl63h_37k_qftv40000gn/T/pip-build-vxx8Ov/google-appengine/setup.py", line 3, in <module>
        ez_setup.use_setuptools()
      File "/Users/user/path to project/project/venv/lib/python2.7/site-packages/ez_setup.py", line 145, in use_setuptools
        return _do_download(version, download_base, to_dir, download_delay)
      File "/Users/user/path to project/project/venv/lib/python2.7/site-packages/ez_setup.py", line 124, in _do_download
        to_dir, download_delay)
      File "/Users/user/path to project/project/venv/lib/python2.7/site-packages/ez_setup.py", line 193, in download_setuptools
        src = urlopen(url)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 154, in urlopen
        return opener.open(url, data, timeout)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 437, in open
        response = meth(req, response)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 550, in http_response
        'http', request, response, code, msg, hdrs)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 475, in error
        return self._call_chain(*args)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 409, in _call_chain
        result = func(*args)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 558, in http_error_default
        raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
    urllib2.HTTPError: HTTP Error 403: SSL is required

----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/88/5jq5gz011sl63h_37k_qftv40000gn/T/pip-build-vxx8Ov/google-appengine/`