pseudo-filter from stdin is broken

[Jan Nieuwenhuizen]

A probably well-meant warning actually crashes
lilypond when processing stdin.

It seems it warns about the fact that
ghostscript - or our ghostscript command -
cannot handle file names that start with "-".

Not sure why we don't rename "-" to "stdin"
and then cat stdin.<the requested output>

14:00:44 address@hidden:~
$ echo '{ a b c }' | LANG= lilypond -
Processing `-'
Parsing...
-:0: warning: no \version statement found, please add

\version "2.12.3"

for future compatibility
Interpreting music... 
Preprocessing graphical objects...
Finding the ideal number of pages...
Fitting music on 1 page...
Drawing systems...
Layout output to 
`-.ps'.../usr/share/lilypond/2.12.3/scm/framework-ps.scm:647:9: In procedure 
simple-format in expression (ly:warning (_ "cannot convert <stdout> to ~S" 
"PDF")):
/usr/share/lilypond/2.12.3/scm/framework-ps.scm:647:9: FORMAT: Missing argument 
for ~S
[1]14:05:20 address@hidden:~

Note that the \version statement is funny, stdin
has no future?

Greetings,
Jan.

-- 
Jan Nieuwenhuizen <address@hidden> | GNU LilyPond - The music typesetter
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