DXF export issue

[adam-urbanczyk]

My use-case has a far smaller work scope: I only need 3D-to-2D projections. Dimensions & annotation are not required. Kind of similar to #1685 except in DXF:

Here is my reduced workflow:

1. On-demand 3rd angle projections of the same part to three separate DXF files (e.g. top.dxf, left.dxf, front.dxf)

2. Write a simple (Python/bash) script to embed the DXF files into a ISO titleblock template, e.g. this file

3. Open the output DXF in the LibreCAD GUI.

4. Manually draw dimensions on the titleblock with command prompt or with the mouse.

I managed to simulate #1685 with the following code:

def exportDXF3rdAngleProjection(my_part, prefix: str) -> None:
    viewpoint = {
        'top': (0, 0, 1),
        'left': (1, 0, 0),
        'front': (0, 1, 0),
    }
    for name, direction in viewpoint.items():
        cq.exporters.exportDXF(
            mounting_rail.rotateAboutCenter(direction, 90),
            f"{prefix}{name}.dxf",

            # Note: exportDXF is missing the following parameter.
            #opt={
            #    "projectionDir": direction,
            #},
            doc_units=6,
        )

but the issue is cq.exporters.exportDXF messed up the countersunk holes:

Question: is it a known issue in cadquery? Is there a bug report on Github that I can keep track of?

Originally posted by @antonysigma in #122