Moving nodes around the tree in a scene with baked lightmap triggers lightmap reimport

[atirut-w]

Godot version

v4.2.beta.custom_build [a60fc7f]

System information

Godot v4.2.beta (a60fc7f) - Windows 10.0.22621 - Vulkan (Forward+) - dedicated AMD Radeon RX 6700 XT (Advanced Micro Devices, Inc.; 27.20.21034.37) - AMD Ryzen 7 5700X 8-Core Processor (16 Threads)

Issue description

When you move any node around within the tree of a scene with baked lightmap, a reimport of the lightmap file will be triggered.

Steps to reproduce

1. Set up a scene with some lightmapped meshes. Also create one dynamically lit object for testing reason.
2. Bake lightmap
3. Move any node around in the scene tree
4. A reimport will be triggered.

Minimal reproduction project

Lightmap Reimport.zip

[AThousandShips]

Can you reproduce this on earlier development snapshots or versions?

[atirut-w]

I can reproduce this on 4.2 Beta 1.

[AThousandShips]

And further back?

[atirut-w]

I went back to b137180 and it seems to be present. Further testing will have to wait for tomorrow since it's very late at night here.

[bitsawer]

There is a PR that might also improve this behavior, but I haven't tested it: #77788

[atirut-w]

Found a good commit. I'll start a git bisect and see what caused this bug. Will also check out #77788.

Commit SHA in case anyone want it: ce236a6
New good commit: fab1c6f
New bad commit: 3a990e3

[atirut-w]

It seems that this was exposed (read: not introduced) in 42a3108, and that #77788 not only improved the behavior, but actually fixed it.