Silly merge of notes in the same Staff-context when producing midi

[Heikki Johannes Junes]

The following examples should produce exactly same midi-events. However,
in the first score there is some merge of notes which prevents playing the
"g,"-note. Instead, the second score is played exactly the right manner!

\score {
    \context PianoStaff <
        \context Staff = upper <
            \context Voice = i { \notes \relative c'' { e4 g, e' } }
            \context Voice = ii { \notes \relative c'' { g2  g } }
        >
        \context Staff = lower <
        >
    >
    \midi{}
}
\score {
    \context PianoStaff <
        \context Staff = upper <
            \context Voice = i { \notes \relative c'' { e4 g, e' } }
        >
        \context Staff = lower <
            \context Voice = ii { \notes \relative c'' { g2  g } }
        >
    >
    \midi{}
}

I hope that this small example helps somebody to fix this small bug
concerning polyphonic piano music.

--
      Heikki Junes