More "cannot resolve rest collision" warnings

[Daniel Rosen]

In the example below, I'd like to use the music that appears after the barline 
because it lines up the rests visually with their respective voices. It looks 
exactly the way I want it to, but I'm getting this warning:

document.ly:6:7: warning: cannot resolve rest collision: rest direction not set
  g16[ 
       f\rest f] |

How do I make this go away?

%%% Begin example
\version "2.16.1"

one = \relative c'''' {
  \time 3/16
  \voiceOne
  g16[ r f] |
  g16[ f\rest f] |
}

two = \relative c''' {
  \voiceTwo d16 r r |
  \oneVoice d16 r r |
}

<<
  \new Voice { \one }
  \\
  \new Voice { \two }
>>
%%% End example

DR