prop_cycler validation over-zealous

[tacaswell]

To help us understand and resolve your issue please check that you have provided
the information below.

• Matplotlib version, Python version and Platform (Windows, OSX, Linux ...)
  • 2.x
• How did you install Matplotlib and Python (pip, anaconda, from source ...)
• from source
• If possible please supply a Short, Self Contained, Correct, Example
  that demonstrates the issue i.e a small piece of code which reproduces the issue
  and can be run with out any other (or as few as possible) external dependencies.

import numpy as np
import numpy as np
import matplotlib.pyplot as plt
from cycler import cycler
plt.style.use([
    'seaborn-paper', {'axes.prop_cycle': (
        cycler('color', ['k'])*
        cycler('linewidth', [2,1])*
        cycler('dashes', [[],[13,2],[8,3,1,3]]))}])

a = np.array((0.,5.))
plt.plot(a,a, linewidth=6)
plt.plot(-a,a, dashes=[])

• If this is an image generation bug attach a screenshot demonstrating the issue.
  • raises
• If this is a regression (Used to work in an earlier version of Matplotlib), please
  note where it used to work.
  • worked in 1.5.3

[tacaswell]

Discovered via https://stackoverflow.com/questions/40470827/pyplot-plot-doesnt-respect-keyword-arguments