Bug report

Setting categorical units on an axis that is shared across subplots updates the units on its siblings, but not the order of the units.

Code for reproduction

f, axs = plt.subplots(1, 2, sharex=True)
axs[0].xaxis.update_units(["a", "c", "b"])
axs[1].plot(["a", "b", "c"], [1, 2, 3])

Actual outcome

Expected outcome

Compare to:

f, axs = plt.subplots(1, 2, sharex=True)
axs[0].xaxis.update_units(["a", "c", "b"])
axs[0].plot(["a", "b", "c"], [1, 2, 3])

Matplotlib version

• Operating system:
• Matplotlib version: 3.3.0
• Matplotlib backend (print(matplotlib.get_backend())): pylab inline
• Python version: 3.8