Log Message:
Updated py-test-cov to 2.3.1.

2.3.1 (2016-08-07)
------------------

* Fixed regression causing spurious errors when xdist was used. See `#124
  <https://github.com/pytest-dev/pytest-cov/issues/124>`_.
* Fixed DeprecationWarning about incorrect `addoption` use. Contributed by \ 
Florian Bruhin in `PR#127
  <https://github.com/pytest-dev/pytest-cov/pull/127>`_.
* Fixed deprecated use of funcarg fixture API. Contributed by Daniel Hahler in \ 
`PR#125
  <https://github.com/pytest-dev/pytest-cov/pull/125>`_.

2.3.0 (2016-07-05)
------------------

* Add support for specifying output location for html, xml, and annotate report.
  Contributed by Patrick Lannigan in `PR#113 \ 
<https://github.com/pytest-dev/pytest-cov/pull/113>`_.
* Fix bug hiding test failure when cov-fail-under failed.
* For coverage >= 4.0, match the default behaviour of `coverage report` and
  error if coverage fails to find the source instead of just printing a warning.
  Contributed by David Szotten in `PR#116 \ 
<https://github.com/pytest-dev/pytest-cov/pull/116>`_.
* Fixed bug occurred when bare ``--cov`` parameter was used with xdist.
  Contributed by Michael Elovskikh in `PR#120 \ 
<https://github.com/pytest-dev/pytest-cov/pull/120>`_.
* Add support for ``skip_covered`` and added ``--cov-report=term-skip-covered`` \ 
command
  line options. Contributed by Saurabh Kumar in `PR#115 \ 
<https://github.com/pytest-dev/pytest-cov/pull/115>`_.