accidentals in chords

[Stefan Thomas]

Dear lilypond-users,
I have question about the accidentals in the "neo-modern-style". In my
opinion, it should also add extra-naturals, if you have chords with
cis and c' together. Unfortunately it does not do this, as the below
quoted snippet shows.
How this can be changed?

\version"2.12.0"
\new Staff \relative {
        #(set-accidental-style 'neo-modern)
bes'4 b, g' f <b, f' g bes>1 }