Discovered a strange bug when testing the auto rotation of EXIF orientation images, it looks like the pixels are shifting for some images.

Test images:
https://github.com/recurser/exif-orientation-examples

Test case:
bug.zip

Usage:

• composer install
• php test.php
• see the output folder

Output as GIF slideshow:

^{It's GIF so horrible quality, but you clearly see the (random?) pixel shifts by the portrait images.}

Tested with libvips 8.6.0-alpha1 and 8.5.7, the output is the same.