The following:

import numpy as np
import matplotlib.pyplot as plt

mu, sigma = 100, 15
x = mu + sigma * np.random.randn(10000)
fig = plt.figure()
ax = fig.add_subplot(111)
n, bins, patches = ax.hist(x, 50, normed=1, histtype='step')
plt.ylim(-.005, plt.ylim()[1])
plt.show()

produces this in 1.1.0 (although I manually zoomed in here since 1.1.0 didn't set the upper limit on ylim correctly):

but at the HEAD the path is now closed by a bottom line:

Would this be considered as a regression? Could an argument be created to allow the user to decide if the bottom line should be displayed? In most of my plots showing a step histogram (usually overlaid on some filled histograms) the bottom line is not desirable.

I originally asked how to remove the bottom line on SO (thanks to @tacaswell for the answer!):

http://stackoverflow.com/questions/16862501/draw-a-step-histogram-without-closing-the-polygon-with-the-bottom-line