title: Pip Install Twisted Error 1
body: <p>When using <code>pip install Twisted</code> in virtualenv on Mac osx 10.9.4, I get this result: </p>
  
  <p><code>Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/9r/3b500gbs3093ms87mqqbckr80000gn/T/pip-build-doynftp7/twisted/</code></p>
  
  <p>I am not sure how to resolve. I used easy_install, but I get a SSL verification issue. Anyone have similar issue? The rest of error message is below. </p>
  
  <pre><code> Collecting twisted
   Using cached Twisted-16.6.0.tar.bz2
   Complete output from command python setup.py egg_info:
  Download error on https://pypi.python.org/simple/incremental/: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749) -- Some packages may not be found!
  Couldn't find index page for 'incremental' (maybe misspelled?)
  Download error on https://pypi.python.org/simple/: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749) -- Some packages may not be found!
  No local packages or working download links found for incremental&gt;=16.10.1
  Traceback (most recent call last):
    File "&lt;string&gt;", line 1, in &lt;module&gt;
    File "/private/var/folders/9r/3b500gbs3093ms87mqqbckr80000gn/T/pip-build-lqvxc68n/twisted/setup.py", line 21, in &lt;module&gt;
      setuptools.setup(**_setup["getSetupArgs"]())
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/distutils/core.py", line 108, in setup
      _setup_distribution = dist = klass(attrs)
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/setuptools/dist.py", line 317, in __init__
      self.fetch_build_eggs(attrs['setup_requires'])
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/setuptools/dist.py", line 372, in fetch_build_eggs
      replace_conflicting=True,
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/pkg_resources/__init__.py", line 851, in resolve
      dist = best[req.key] = env.best_match(req, ws, installer)
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/pkg_resources/__init__.py", line 1123, in best_match
      return self.obtain(req, installer)
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/pkg_resources/__init__.py", line 1135, in obtain
      return installer(requirement)
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/setuptools/dist.py", line 440, in fetch_build_egg
      return cmd.easy_install(req)
    File "/Users/Complex-Cauchy/1/lib/python3.6/site-packages/setuptools/command/easy_install.py", line 668, in easy_install
      raise DistutilsError(msg)
  distutils.errors.DistutilsError: Could not find suitable distribution for Requirement.parse('incremental&gt;=16.10.1')
   ----------------------------------------
  </code></pre>
  
  <p><code>Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/9r/3b500gbs3093ms87mqqbckr80000gn/T/pip-build-lqvxc68n/twisted/</code></p>
  
  <p>Running <code>openssl s_client -showcerts -connect pypi.python.org:443
  </code> returns the following: </p>
  
  <pre><code> CONNECTED(00000003)
   depth=1 /C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 Extended     Validation Server CA
   verify error:num=20:unable to get local issuer certificate
   verify return:0
   ---
   Certificate chain
    0 s:/businessCategory=Private Organization/1.3.6.1.4.1.311.60.2.1.3=US/1.3.6.1.4.1.311.60.2.1.2=Delaware/serialNumber=3359300/street=16 Allen    Rd/postalCode=03894-4801/C=US/ST=NH/L=Wolfeboro/O=Python Software Foundation/CN=www.python.org
    i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 Extended Validation Server CA
    -----BEGIN CERTIFICATE-----
    MIIIWjCCB0KgAwIBAgIQCXCW7BLw16II/CMOsOFe/jANBgkqhkiG9w0BAQsFADB1
    ..
   -----END CERTIFICATE-----
   1 s:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 Extended Validation Server CA
   i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV Root CA
   -----BEGIN CERTIFICATE-----
  MIIEtjCCA56gAwIBAgIQDHmpRLCMEZUgkmFf4msdgzANBgkqhkiG9w0BAQsFADBs
  ....
  -----END CERTIFICATE-----
   Server certificate
   subject=/businessCategory=Private Organization/1.3.6.1.4.1.311.60.2.1.3=US/1.3.6.1.4.1.311.60.2.1.2=Delaware/serialNumber=3359300/street=16 Allen Rd/postalCode=03894-4801/C=US/ST=NH/L=Wolfeboro/O=Python Software Foundation/CN=www.python.org
  issuer=/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 Extended  Validation Server CA
  ---
  No client certificate CA names sent
  ---
  SSL handshake has read 3524 bytes and written 456 bytes
  ---
  New, TLSv1/SSLv3, Cipher is AES128-SHA
  Server public key is 2048 bit
  Secure Renegotiation IS supported
  Compression: NONE
  Expansion: NONE
  SSL-Session:
  Protocol  : TLSv1
  Cipher    : AES128-SHA
  Session-ID: BC7695FF86D2B82B20468A13E3F3E13AE23776B500E64665305EEBAF49BB54D1
  Session-ID-ctx: 
  Master-Key:8D25B34237A3C74E90317D87BA74A2AAF0E8C424FB2ADE3D72E5F234D5E043C4527641290B928B3A22 1BE7D44116CFB1
  Key-Arg   : None
  Start Time: 1487035770
  Timeout   : 300 (sec)
  Verify return code: 0 (ok)
  </code></pre>