- Import the attached WhiteSquare512.jpg image in a project
- Set texture type to Advanced and Import Type - Sprite Mode to Multiple
- Click on the Sprite Editor button to edit the sprites
- Create a sprite from the texture by dragging a smaller rectangle with your mouse
- Close the Sprite Editor window
- Choose Apply when asked if you want to keep the changes or not

Notice in the Console the following assert:
"importer.GetNPOTScale() == TextureImporter::kNPOTKeep

(Filename: C:/buildslave/unity/build/Editor/Src/AssetPipeline/SpriteFrameMetaData.cpp Line: 22)"