Accidental placement in voiceTwo vs. another staff

[James Harkins]

Is this a known bug?

It looks like LP is trying to avoid a collision between the natural sign in the 
top staff's voiceTwo and the sharp sign in the bottom staff. But of course they 
are nowhere near touching, so there should be no need for collision avoidance.

(Sorry I'm on a slightly older stable version, and sorry for the noise if it's 
already fixed.)

\version "2.16.1"
\include "english.ly"

global = {
  \time 3/4
  \numericTimeSignature
  \key ef \major
  s2.*2
  \key cs \minor
  s2.
}

\score {
  \new PianoStaff <<
    \new Staff <<
      \global
      \new Voice \relative c''' {
        \voiceOne
        g8 af f ef df4 ~
        df2 cs4
        e2.
      }
      \new Voice \relative c'' {
        \voiceTwo
        r2 df8 c
        b_"b's natural sign is too far left" a gs fs e ds
        <cs e gs>2.
      }
    >>
    \new Staff <<
      \global
      \relative c {
        \clef bass
        ef2 f4
        fs4 gs4 gs,4
        cs2.
      }
    >>
  >>
}

hjh