Simultaneous notes are not properly aligned horizontally

[Kai Ruhnau]

Hi,

I have got a piece with a lot of unisons and seconds appearing in each
choral voice. These don't get properly aligned horizontally between the
voices. The following example shows that problem:

\version "2.16.2"

\score {
    <<
    \new Voice {<a' b'>1 <a' b'>2}
    \new Voice {<b' c''>1 <b' c''>2
    }>>
}

When the stem goes up, the second note is placed on the right of the stem.
When the stem goes down (and is on the left side of the note head) the
additional note is placed to the left of the stem.

This looks especially strange for whole notes.

Best regards
Kai