See https://www.mediawiki.org/wiki/Requests_for_comment/Square_bounding_boxes for context.
The "upright" option is currently misnamed: it doesn't do anything special for upright images, it just scales the default width-based thumbnail size.
It should use a square bounding box.
Version: 1.24rc
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=63903