Perspective LPE shrinks object on flip (horizontal/vertical)

Originally reported by @datalot, split out from inbox#3164 (moved)

Steps to reproduce:

  • open Inkscape
  • create a path
  • apply Perspective LPE (using LPE dialog)
  • move the perspective lpe handles a bit
  • horizontally or vertically flip the object

What happened?

  • the scale shrinks massively
  • this is because the perspective handles are shrunk down a lot
  • Peek_2020-06-28_18-05.gif
  • Peek_2020-06-28_18-07.gif

What should have happened?

  • flipped while retaining proper size

Inkscape Version and Operating System:

  • 1.1-dev (62b2e789, 2020-08-04) Linux Mint 20
  • 1.0 (4035a4fb, 2020-05-01) Linux Mint 20

Bisection points to commit 1c6eacc9

Author: Jabier Arraiza <jabier.arraiza@marker.es>
Date:   Mon Dec 23 22:33:04 2019 +0100

    Fix bugs https://gitlab.com/inkscape/inbox/issues/169 and https://gitlab.com/inkscape/inbox/issues/72