[GUB-2.7.39-1] odd \break behaviour

[Andrzej Kopec]

In following fragment of code \break statement creates additional Staff context 
"from
nowhere", and this Staff context lives until parent StaffGroup lives. 
(GUB-2.7.39-1 under Linux)

/ak/

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\version "2.7.39"
\score {
  {
    \context StaffGroup = "ps"  <<
      \context Staff = "p1" \relative c'' { c4 d e f g2 des }
      \context Staff = "p2" \relative c'  { c4 d e f g2 des }
    >>
    
    \break %% causes creation of additionas Staff in the "ps" context
    
      \context StaffGroup = "ps" <<
      \context Staff = "p1" \relative c'' { ges4 f es des c1 }
      \context Staff = "p2"  \relative c' { ges4 f es des c1 }
    >>
    
  }
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%