pageBreak causes multiple ChoirStaff or StaffGroup System Start Delimiters

[Patrick Karl]

The following snippet generates a StaffGroup with two staves followed by a second similar StaffGroup on a second page:

\score {
    {
      \new StaffGroup <<
          \new Staff c''1
          \new Staff c''1  >>
      \new StaffGroup <<
          \new Staff {  \pageBreak d''1 }
          \new Staff d''1 >>
   }
}

Here is an image of the beginning of the second system generated by the above snippet:

Unfortunately, the second StaffGroup has not one but two System Start Delimiters.  If a third such StaffGroup were generated, it would have three System Start Delimiters, etc., etc.,  The same problem occurs with ChoirStaff and appears to happen no matter what the System Start Delimiter is.

Does anyone have a workaround for this problem?

Above image also attached.

Screen Shot 2019-08-09 at 11.19.38 AM.png
Description: PNG image