\version "2.11.57"
{
  % \voiceOne immediately before a grace does not properly set the stem direction.
  % Other properties set by \voiceOne (like rest placement) work just fine:
  \voiceOne  \appoggiatura e''4 f'' r e'' r |
  
  \oneVoice R1 | % let the \oneVoice take effect
  
  % If there is any note/rest between voiceOne and the grace command, everything works:
  \voiceOne r4 \appoggiatura e''4 f'' r e'' |
}