Log Message:
Update to 13.1.2:

13.1.2 (2015-08-23)
~~~~~~~~~~~~~~~~~~~

* Upgrade pip to 7.1.2.

13.1.1 (2015-08-20)
~~~~~~~~~~~~~~~~~~~

* Upgrade pip to 7.1.1.

* Upgrade setuptools to 18.2.

* Make the activate script safe to use when bash is running with ``-u``.