Mensural breve in Tempus perfectum

[Francisco Vila]

Hello. Does anyone know what's wrong here? see
http://lilypond.org/doc/v2.12/Documentation/user/lilypond/Typesetting-mensural-music#Mensural-time-signatures

\version "2.12.3"

%tempus perfectum

%this should equal three semibreves
brevTP = #(ly:make-duration -1 0 3 2)

\score {
   <<
  \new MensuralStaff {
    \time 3/2
    \relative c' {
      c\brevTP^"this should equal three semibreves" c\brevTP  }
  }

  \new MensuralStaff {
    \time 3/2
    \relative c' {
      c1^"but it seems to equal two semibreves" c c c c c }
  }
>>
}


-- 
Francisco Vila. Badajoz (Spain)
www.paconet.org , www.csmbadajoz.com