Ugly collisions when using manual beaming across rests

[Valentin Villenave]

Greetings,

%{
In the following snippet, manual beams over rests force them be
printed higher than their normal placement. However, the other grobs
(accidentals, and even notes) don't take this change into account when
spacing is tight, thus provoking unwanted collisions.

(I added accidentals to make the collisions obvious, but if you remove
them, the b in the chord still collides with the rests).
%}

\version "2.11.32"
\paper {
ragged-right = ##t
}

{
  \repeat unfold 20 {<f'' b'' c''' f'''>16[ r <f'' bes'' c''' f'''>
<f'' b'' c''' f'''>]}
}