Wierd behaviour of \header in \bookpart in \version 2.12.2

[Bernard Hurley]

Hi,

Inside a bookpart only the last header block is seen. In the following
snippet, title and composer appear but _not_  poet.

Bernard

\header { title = "Test" }
\bookpart {
  \header { poet = "Someone" }
  \header { composer = "Me" }
  { c'4 }
}