Please describe the problem:
If you choose as a Background in gnome-shell a JPEG image that has an EXIF rotation bit set, the image will use as a landscape image while in fact it has a portrait orientation.

Steps to reproduce:
1. Take any portrait JPEG image with orientation set in EXIF.
2. Set it as a background (e.g. with "Change background").

Actual results:
The correct image is visible on the desktop, but it is not rotated (it's treated as a portrait image).

Expected results:
I expected the correct image to both be visible and correctly rotated (the portrait orientation should be kept).

Does this happen every time?
Yes.

Other information:
An orientation detection works fine in most of the image viewers (including Shotwell, GIMP or Shutter).
Examples pictures in different orientations:
https://github.com/recurser/exif-orientation-examples
An explanation of the Orientation tag in exif:
https://beradrian.wordpress.com/2008/11/14/rotate-exif-images/

The description has been based on a related issue for libgnome-desktop - bug 516177.