Could not fetch URL https://pypi.python.org/simple/tensorflow/: There was a problem confirming the s

  Could not fetch URL https://pypi.python.org/simple/tensorflow/: There was a problem confirming the ssl certificate: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:645) - skipping

Try to run this command from the system terminal. Make sure that you use the correct version of 'pip' installed for your Python interpreter located at '/usr/local/bin/python3.5'.

Collecting matplotlib
  Could not fetch URL https://pypi.python.org/simple/matplotlib/: There was a problem confirming the ssl certificate: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:645) - skipping

  Could not find a version that satisfies the requirement matplotlib (from versions: )
No matching distribution found for matplotlib

原因：升级的pip是python2.7，需要指定python3的pip，执行下面命令。

curl https://bootstrap.pypa.io/get-pip.py | python3