Despite the fact that OP is related to the message that answered a slightly different question regarding the histogram step graphs, here is a solution for any user passing here who specifically tries to turn off the complexion in pyplot.barbar graphs:
import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(1, 10, 10)
y = np.random.randn(10)
z = np.random.randn(10) * 2
plt.bar(x-0.2, y, width=0.4, edgecolor='purple', color='None')
plt.bar(x+0.2, z, width=0.4, edgecolor='darkorange', color='None')
plt.show()

, matplotlib.lines.Line2D, linewidth, linestyle, alpha ..
plt.bar(x-0.2, y, width=0.4, edgecolor='purple', color='None',
linewidth=0.75, linestyle='--')
plt.bar(x+0.2, z, width=0.4, edgecolor='darkorange', color='None',
linewidth=1.5, linestyle='-.')
plt.show()
