Skip between \marks will be ignored

[Simon Albrecht]

Hello,

If there are only skips (s) between two \mark commands, these will be ignored, 
a warning given about simultaneous marks, and everything following in this 
(input) music expression will not be engraved. It boils down to the following:

\version "2.19.22"
% same with 2.18

%{

The problem:
Warning about Two simultaneous mark events &c.
All the following music will be junked

Test cases:

Same duration       – \default given     – problem
Same duration       – \default not given – no problem
Different durations – \default given     – problem
Different durations – \default not given – problem

%}

{
  \mark
  s4
  \mark \default
  s
}

I submitted Issue 4472 
<https://code.google.com/p/lilypond/issues/detail?id=4472>, but wanted 
to ‘announce’ it here also. It’s quite confusing that it interferes with 
\default given or not, isn’t it?

Best regards, Simon