Empty markup lines behavior change (maybe regression) in dev (2.21.7) than stable (2.20.0)

[K.L.]

Try engrave this ly code:

\version "2.20.0"
>
> \header {
>   title = \markup \column {
>    \line { "Minuet" }
>    \line { "" }
>    \line { "" }
>   }
>   subtitle = "A study in accent and in the correct timing of half beats"
> }
>


{s}


By lilypond v2.20.0:
[image: image.png]

By lilypond v2.21.7:
[image: image.png]

Sometimes a ly code converted from music sheet software (like Finale), and
their composers prone to typeset casually like this. It's better to
keep accordance with the original appearance.

And I noticed that in SVG results of the new version, every individual
element was wrapped by a <g>, what's the design intention? Something will
transform double times?