bug#33631: 26.1.90; Image mode should keep scale on auto-revert

[Carlos Pita]

I'm refreshing the image from an org mode code block or,
alternatively, an interactive ipython buffer, so all of my previous
attempts have indeed been with an unselected image mode buffer.

Nevertheless I tried the same but updating the image from an external
process while keeping the image buffer selected and the behavior is
the same, the image is resized to the default (initial) size.