Boolean operations on ellipses with transform="scale(-1)" distort the shape

Summary:

If a ellipse with transform="scale(-1)" is used in a boolean operation, its shape gets distorted.

Steps to reproduce:

  • open Inkscape
  • create a circle/ellipse
  • scale it over zero (e.g. drag a scaling corner arrow over the opposite corner arrow)
  • duplicate it and shift the duplicate horizontally so that the two overlap a bit.
  • select both circles and choose Path > Union

What happened?

  • The resulting shape does not look like two circles combined (some of the smooth nodes became corners)

What should have happened?

  • I expect a path with only two corner nodes and six smooth nodes

Sample attachments:

distorted_union.svg

Version Info:

- Inkscape Version: ... 1.0.2 (e86c870879, 2021-01-15)
- Operating System: ... Gentoo Linux
- Operating System version: ... desktop - 17.1 - stable