Operating system: Windows 10
Graphics card: NVIDIA GeForce GTX 970
Broken: 2.80, hash: c 93592109138, master, 2019-05-24
Short description of error
If an object with outward facing normals is scaled by a negative factor, the normal direction gets inverted.
This is however not shown in blender, since these objects still show up with outwards facing normals, once they are exported into a external application they show up as inverted.
Exact steps for others to reproduce the error
Enable face orientation under viewport overlays settings
Dublicate or link the default cube
Scale dublicate/link by a negative factor
The scaled cube shows up red because of it's inward facing normals.
The scaled cube still shows up blue as if it's normals were facing outwards.