Text object changes size upon moving (with transform attribute)

Steps to reproduce:

1. Open bug-text-changes-size.svg in Inkscape.
2. Select the "A123" text object.
3. Move it anywhere (e.g. press right arrow key).

What happened?

Text become smaller.

What should have happened?

Text should remain the same size.

This occurs when the text object has a transform=scale() or matrix() attribute.

From what I can tell, the affine transform matrix is correctly being scaled in SPText::set_transform but the font size is not adjusting as it is supposed to.

Inkscape Version and Operating System:

• Inkscape Version: 1.0alpha (61ed6873, 2019-02-12)
• Operating System: openSUSE Tumbleweed
• Operating System version: 20190215

Example file:

bug-text-changes-size.svg