Copy from a file text widget: there is an extra new line on each line

Copy-paste from a file text widget, e.g.:

https://debusine.debian.net/debian/developers/artifact/3317332/

On pasting: there is an extra new line at the end of each line:

Package: tlsh

Version: 5.0.0+ds-1~exp1

Source Version: 5.0.0+ds-1~exp1

Distribution: sid

Machine Architecture: amd64

Host Architecture: amd64

Build Architecture: amd64

Build Type: any