Bug with tremolo and multi-voice with accidentals

[Steven Weber]

Windows XP, Lilypond 2.10.2 and 2.11.1

If you have multiple voices in a bar and one (or both) of them has an 
accidental, the tremolo is positioned poorly.

\version "2.10.2"
\layout { ragged-right = ##t }
\relative c 
{
        \clef bass
        % Notes 1, 2, and 4 are bad.  Note 3 is good
        << { f4 :32 fis : e : eis : } \\ { gis, :32 g : e : e : } >>
}