Thanks very much for attending to the errorbar bar-ends. FYI, I ran the patched code over my own errorbar plots and the refactoring seems to work correctly in all cases.
As Gary noted, recently we changed the way error bars were drawn which
apparently had some unintended consequences. The root of the problem
is related to one that came up earlier on the list about differences
in the way regular lines and marker lines are handled.
Replace matplotlib.axes.Axes.errorbar with the code below. Errorbar
users, I would be much obliged if you test this. I tried all of
Gary's errorbar_demo examples and they appeared to work fine....