Can you also and an entry I CHANGELOG, api_changes.rst and whats_New.rst? The two rst files are under doc.

This is so your new feature gets advertised.

Sorry, I was a little bit busy, and I will be completely offline for the next two weeks (since tomorrow).
I fix style tests failures and add line in api_changes.rst.

For whats_New, I think, it is too small changes
And I don't understand what you mean by 'I CHANGELOG entry'.

Feel free to reject this pull request and make changes yourself, I will happy enough.

That comment should have read:

"Can you also add an entry in CHANGELOG, api_changes.rst and whats_New.rst? The two rst files are under doc."

Sorry for the typos (I think I will blame my phone).

Add line in changelog.
Pythjon 2.7 still failed ( https://travis-ci.org/matplotlib/matplotlib/jobs/20698286 ), and I don't know why :( Failed test does not connected with my changes.

======================================================================
FAIL: matplotlib.tests.test_triangulation.test_tripcolor.test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7/local/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/travis/virtualenv/python2.7/local/lib/python2.7/site-packages/matplotlib-1.4.x-py2.7-linux-x86_64.egg/matplotlib/testing/decorators.py", line 50, in failer
    result = f(*args, **kwargs)
  File "/home/travis/virtualenv/python2.7/local/lib/python2.7/site-packages/matplotlib-1.4.x-py2.7-linux-x86_64.egg/matplotlib/testing/decorators.py", line 201, in do_test
    '(RMS %(rms).3f)'%err)
ImageComparisonFailure: images not close: /home/travis/build/matplotlib/tmp_test_dir/result_images/test_triangulation/tripcolor1.png vs. /home/travis/build/matplotlib/tmp_test_dir/result_images/test_triangulation/tripcolor1-expected.png (RMS 90.068)

[tac edited to add markup]

travis some times generates transient failures (or fails to set it's self up). Don't worry about it in this case.

This looks good to me. The one other thing that is good to have is a test showing the function of the new feature. As you are about to go offline for two weeks, I will take care of the test for this feature.

One last thing I just noticed, if the plot is ccw, should the starting angle also be shifted?

I think not, cause situation simpler if one parameter controls only one thing -- only fractions direction in this case.

Fair point (I had not fully grasped the difference that the starting position was an angle and the wedge sizes were fractions).

I will merge this tonight unless there is protest.