serious bug regarding rest position

[Werner LEMBERG]

% serious
% address@hidden

\version "2.9.10"

\header { texidoc = "
The example below exhibits two serious bugs.

. The default rest position of an upper voice must be
  four staff units higher.

. It is not possible to modify the rest's position.
" }

\paper {
  ragged-right = ##t
}

\relative c''' {
  << { b8[ f' r b,] b8[ f' f\rest b,] } \\
     { s1                             } >>
}

% EOF