breakbefore not working when piece=""

[Panteck]

Windows XP, Lilypond 2.8.4

When piece="", Lily doesn't do a page break.  If piece=" ", a page break is
created, but the spacing is sub-optimal because Lily allocates vertical
space for the space character and associated padding.

Snippet:
\version "2.8.4"

\book
{
\score
{
\new Staff
 <<
  \relative c' { c d e f }
 >>

\header
{
 piece = "First Piece"
}
}

\score
{
\new Staff
 <<
  \relative c' { c d e f }
 >>

\header
{
 breakbefore = ##t
 piece = ""
}
}
}

--Steven