When projection painting a dense mesh a face can be marked PROJ_FACE_DEGENERATE when it is too small. Degenerative faces are handled differently and as documented can create incorrect results. Not sure what these incorrect results are and if there could be a better solution for handling these results. This fix would only mark a face degenerative when all the verts are the same. Reviewed By: Campbell Barton Differential Revision: https://developer.blender.org/D7662