I'm trying to move an edge loop in a mesh that's not aligned to the global axis, but is supposed to have all right angles (since it was created from a cube). Even though I move the loop along the mesh's local Y axis eventually the angles on some edges deviate from 0.000/90.000 degrees as you can see here:
This stops happening for this particular edge loop after I apply the scale translation to this object, but now I'm worried it'll happen to me after I've made a lot more modifications to the mesh and wasn't paying attention to the angles.
Is this actually due to a precision loss or something else? Is applying the scale the best solution, if so I'd like to understand why, if not, what is?
Sample file: https://ufile.io/s7vwy Blender: v2.79