\version "2.11.46"

#(ly:set-option 'debug-skylines #t)

% In this example, the hairpin (broken by a line break) is placed too high in 
% the second and third staff, because apparently the clef and the key signature 
% get in its way... 
\relative b' { 
  \dynamicUp \time 2/4 
  \key a \major
  b\< b\! | b\< b  | \break 
  % Key signature makes the second part of the hairpin move up
  b b\! | \key c \major b\< b | \break
  % clef also causes the problem:
  b b\! | \clef "bass" d,,\< d | \break
  % bass clef works, because its extents do not go beyond the staff lines
  d d\! | 
}