fetachars in title (undefined control sequence)

[Graham Percival]

This example fails to build:
(Lilypond 1.5.74, Debian testing)

-----
\header{ instrument="instruments in B\fetachar\fetaflat" }
\score{ \notes\relative c'' { c } }
----

Error message:
------
Analyzing foo.tex...
Running LaTeX...
LaTeX failed on the output file.
The error log is as follows:

! Undefined control sequence.
\lilypondinstrument ->instruments in B\fetachar 
                                                \fetaflat 
l.13 ...pondtitle\undefined\else\makelilypondtitle
          ...
Traceback (most recent call last):
  File "/usr/local/bin/ly2dvi", line 1021, in ?
    run_latex (files, outbase, extra_init)
  File "/usr/local/bin/ly2dvi", line 722, in run_latex
    raise 'LaTeX error'
LaTeX error
LATEX output to `foo.latex'...
TEX output to `foo.tex'...
-------

HTH,
- Graham