\break and \overrideProperty ignored with \grace on other voice

[Nicolas Sceaux]

While tweaking vertical space in a score, I faced the following problem:

\version "2.7.12"

\paper {
  raggedlastbottom = ##t
  annotatespacing = ##t
  betweensystemspace = 1.0
}

\new Staff <<
  {
    \overrideProperty
    #"Score.NonMusicalPaperColumn"
    #'line-break-system-details
    #'((next-padding . 5.35))
    \skip 1*13 \break

    \overrideProperty
    #"Score.NonMusicalPaperColumn"
    #'line-break-system-details
    #'((next-padding . 5.35))
    \skip 1*14 \break
    
    \overrideProperty
    #"Score.NonMusicalPaperColumn"
    #'line-break-system-details
    #'((next-padding . 5.35))
    \skip 1*14
  }
  {
    \repeat unfold 13 c''1
    \grace c''8 \repeat unfold 14 c''1
    \repeat unfold 14 c''1
  }
>>

In the second system, the second voice starts with a \grace note. The
\overrideProperty is ignored for that system.
If I change:
  \skip 1*14 \break
by:
  \grace s8 \skip 1*14 \break
then all is fine.

I can live with, but I thought it would be better to report it, and
maybe documented.

Similarly, with:
<<
  { \skip 1 \break \skip 1 \break \skip }
  { c1 \grace c8 c1 c1 }
>>
there is no line break after the first whole note.

nicolas