Sage Shell View disables alternative "viewers"

[balbirthomas]

Enabling sage shell view using (add-hook 'sage-shell-after-prompt-hook #'sage-shell-view-mode) results in plots always being displayed as PNG images. For example even after toggling inline images (sage-shell-view-toggle-inline-plots) the images are displayed in a browser as a PNG instead of using the default threejs viewer. Specifying a viewer explicitly using viewer keyword argument of the plot or show command also does not make a difference, regardless of the choice of viewer. This breaks the behavior of a sage REPL.

This seems to have been a regression in recent versions of Sage shell view mode. It used to work just like the Sage REPL previously.