subdivision of beams in 5/16 bar

[Stefan Thomas]

Dear community,
I have a problem with subdivided beams in a 5/16 bar.
I want to have subbeams of irregular length, grouped in 2+3 16ths.
Unfortunately it doesn't work.
Is there a way to realize it?
Here is a short snippet:

\version "2.14.2"
motif =  \relative c' { c16[ d e f g] }
\new Staff {
  \time 5/16
 \motif 
  \set subdivideBeams = ##t
     \context Voice << {\motif} 
       { \set baseMoment = #(ly:make-moment 1 8) s8 
       \set baseMoment = #(ly:make-moment 3 16) s8. % only two notes are beamed together, not three!
 }>>    
}