Bug report

Describe the bug

When rotating images using Vips with nearest neighbour interpolation the result has inconsistencies.

This is especially obvious when rotating symmetrical pixel art.

To Reproduce
Steps to reproduce the behavior:

1. Use Image of ladder at bottom
2. Use Configuration interpolate: nearest and rotate 45 degrees
3. See error

Or with the Ruby binding:

ladder = Vips::Image.new_from_file "./ladder.png"
rotated = ladder.rotate 45, interpolate: Vips::Interpolate.new(:nearest)
rotated.write_to_file "./rotated.png"

Expected behavior

Of course nearest neighbour produces artefacts, but I expect them to be symmetrical when the image being rotated is symmetrical.

Actual behavior

There are various discrepancies throughout.

Screenshots

Environment

• OS: macOS 12.4 (21F79)
• vips-8.12.2-Tue Jan 25 09:34:32 UTC 2022

Additional context

ImageMagick produces symmetrical results when using nearest neighbour. However when using "integer" it produces results more like Vips:

Original ladder image:

Or if theres a different way to rotate 1 bit pixel art I'd love to know :)