Bug report

Bug summary

Setting ha="right" through the prop kwarg breaks AnchoredText placement.

Code for reproduction

import matplotlib.pyplot as plt
from matplotlib.offsetbox import AnchoredText

prop = {"ha": "right", "bbox": {"lw": 0.5, "facecolor": "white"}}
text_box = AnchoredText("test\ntest long text for ha", prop=prop, loc="upper right", pad=0.2)
plt.gca().add_artist(text_box)

Actual outcome

Expected outcome

I was expecting the text box to end up in the same place it does when not setting ha="right":

Matplotlib version

• Operating system: macOS 10.15.6
• Matplotlib version: 3.2.1 (pip-installed)
• Matplotlib backend: module://ipykernel.pylab.backend_inline
• Python version: 3.6.10