SVG1.2 flowed text created in Inkscape 0.48 rendered differently in current versions

Migrated from: https://bugs.launchpad.net/inkscape/+bug/1571955

Steps to reproduce:

• open Inkscape
• open text file
• compare rendering to 0.48 rendering

What happened?

file	0.48.1	current / 0.91 onwards

Notable differences: The "DE US" text in the bottom left is displaced vertically, and the "WARNUNG" text is missing. Also the font size is different, but that might be due to the unit conversion.

What should have happened?

The rendering should be identical.

• For the "WARNUNG" text, the flowRegion is too small (vertically) for the first line to fit in 0.91+, but the line fits in 0.48. #1679 (moved) makes the user think the text is gone completely.
• The flow rect of the "DE US" text seems to be slightly lower than the text itself (screenshot from 0.48.1): .
  In 0.91+, the text is moved downwards to fit the flow rect.

Inkscape Version and Operating System:

• Inkscape Version: 1.1-dev (2a5d477, 2020-01-18)
• Operating System: Windows 10
• Operating System version: 10.0.18362

Summary of comments: Confirmed in

• Windows 7, Inkscape trunk rev. 14859.
• 0.91 on Windows
• Inkscape 0.92.3(Windows 7)