Thanks. I'll incorporate this in the huge stack of other style changes we are doing for 2.0.

It might be helpful to update the test images in a separate commit so we can see and review the changes here...

Thanks. This for the most part looks good. The only change I would suggest is that instead of hardcoding b, which will always be blue, we should use [0] after #5674 (or something like it) is merged.

ping @phobson The color cycle color selector is now merged (as 'C0', 'C1', ...)

thanks. @tacaswell. should I rebase off of master or 2.x?

as this PR is against master, rebase on master

Looks like the image tests are not using the classic style so we will need to also update the test images or switch the boxplot image tests to use the classic style.

prefixed b2c8cca as "WIP" since:

1. there's gotta be a better way; and
2. there has to be some redundency with the style checking in Axes.boxplot. IOW, some of the style checking should be moved from boxplot to bxp.

I've add some TODO's to the original message up top

Just the test images:
b2d20e8

Locally I am seeing

matplotlib/lib/matplotlib/__init__.py:1096: UserWarning: Bad val "auto" on line #341
        "boxplot.flierprops.markerfacecolor: auto
"
        in file "/home/tcaswell/source/p/matplotlib/lib/matplotlib/mpl-data/stylelib/classic.mplstyle"
        Key boxplot.flierprops.markerfacecolor: auto does not look like a color arg

Closing this in favor of #6481