collision between rest of one voice and the notes of the other voice

[Michael Kiermaier]

Hello,

it's me again.

I ran into this problem:

\relative c' { << {c c c c} \\ {R1} >> }

In the output there is a collision between the rest of the second voice and 
the notes of the first voice.

The right solution would be to put the rest on a ledger line and to lower it 
until no collision occures.

Is there a reason why lilypond doesn't to that?
Is it possible to force lilypond to put the rest on a ledger line? Or at least 
to correct the output somehow manually?


~michael