**System Information**
Operating system: Linux-4.13.10-041310-generic-x86_64-with-debian-stretch-sid 64 Bits
Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.67
**Blender Version**
Broken: version: 2.80 (sub 73), branch: blender2.7, commit date: 2019-05-30 22:28, hash: `rBfc336f973d52`
**Short description of error**
I have an object, that has a facemap (and faces assgined to it). Alternatively I have on object and have run `bm.faces.layers.face_map.verify()` on its mesh (even without the object having any face map).
If I then add a boolean mod to either of them, and use a second, new object, where face maps were never touched, and if I then apply the boolean mod, the faces of the new object will have a face map index of 0 on the new, booleaned mesh.
This then leads to the new faces being associated with a facemap they haven't been a part of before. The face map indices of the new faces should stay at -1, as they were before the boolean.
[[ https://www.youtube.com/watch?v=0mk5lwoEMMk | video demo ]]
{F7081376}
**Exact steps for others to reproduce the error**
* open the blend file above
* apply the boolean mod on the cube to the right
* go into edit mode and select the face map
* the new faces are part of the pre-existing face map, despite thefact that this face map did not exist on the (second) object and the faces haven't ben assigned to any face map
* apply the boolean mod on the cube to the left
* go into edti mode, create a new face map and select its faces
* the new faces are part of the new face map, without having been assigned to it