Accidentals placed inconsistently in ChordNames

[Ralf Kleineisel]

What steps will reproduce the problem? 
(Please attach or insert a small .ly fragment to duplicate)

\new ChordNames {
  \override ChordName #'font-size = #+5
  \chordmode {
    fis2:m
  }
  \override ChordName #'font-size = #-5
  \chordmode {
    fis2:m
  }
 \germanChords
 \override ChordName #'font-size = #+5
   \chordmode {
     fis2:m
   }
   \override ChordName #'font-size = #-5
   \chordmode {
     fis2:m
   }
}

What is the expected output? What do you see instead?
(Please attach a small output image in PNG or PDF file to show the problem)

http://www.kleineisel.de/ralf/chord_test.png

The accidentals are placed inconsistently when using different font sizes and
with/without \germanChords.

What version of LilyPond are you using?
Tested with 2.11.44 and 2.10.33

On what operating system? 
Fedora 8 i386

Please provide any additional information below.