Style name not set

There seems to be a regression on version 3.1.3 as compared to 3.1.2.

When I change the style of a cell, the style name is not updated.

The following script can be used to replicate the issue:

from openpyxl import load_workbook
from openpyxl import __version__

print(__version__)

input_path = "bigfoot.xlsx"
output_path = f"output_{__version__}.xlsx"

wb = load_workbook(input_path)

ws = wb['sheet #0']
print(ws['A1'].style)
ws['A1'].style = 'Bad'
print(ws['A1'].style)

wb.save(output_path)

In 3.1.2 I get as output:

3.1.2
Normal
Bad

In 3.1.3 I get:

3.1.3
Normal
Normal