Stem length on beamed notes incorrect in 2.13.61

[Nick Payne]

A bar excerpted from the Mertz guitar transcription of Ständchen. When I 
last worked on this score about ten months ago, using 2.13.27, I didn't 
have the problem with the beam on the notes in the middle voice being 
placed below the stem of the note in the lower voice - the beam was 
placed along the bottom line of the stave - see 2.13.27.png, a screen 
shot from the PDF I made at the time:

\version "2.13.61"

\relative c'' {
    \time 3/4
<<
    { cis'2. }
    \\
    { a,,2. }
    \\
    { \stemDown a''8 e <a cis,> e <a cis,> e }
>>
}

Nick

test.preview.png
Description: PNG image

2.13.27.png
Description: PNG image