Exported STEP model is not correct when tag is used

I followed the example https://cadquery.readthedocs.io/en/latest/examples.html#tagging-objects and can produce the result as expected in cq-editor.

I then exported the model to a STEP file. Somehow, it gave the drillings instead.

Here is the script I used. I'm wondering if this is an issue. Thanks in advance.
```python
import cadquery as cq

result = (cq.Workplane("XY")
# create a triangular prism and tag it
.polygon(3, 5).extrude(4).tag("prism")
# create a sphere that obscures the prism
.sphere(10)
# create features based on the prism's faces
.faces("X", tag="prism").faces(">Y").workplane().circle(1).cutThruAll()
)
show_object(result)

cq.exporters.export(result, "result.step")
```