Broken: 2.77a - 2.77 last build bot
Short description of error
Nested boolean does mess normals of PARENT of hole object !
Exact steps for others to reproduce the error
Setup achipack from https://github.com/s-leger/archipack/tree/boolean_mess
In T panel under Create, Use draw a wall click, drag and release to create a wall, then use draw doors/windows to slap object on the wall.
Select the wall, and in T + tools panel click on autoboolean.
Look at window frame.