Comment # 3 on bug 947842 from Takashi Iwai

(In reply to Dominique Leuenberger from comment #2)
> (In reply to Takashi Iwai from comment #0)
> 
> > The likely reason is that the package doesn't update the gtk icon theme.  It
> > should have %icon_theme_cache_post and %icon_theme_cache_postun in post and
> > postun triggers.
> 
> This is easy to confirm: do the icons show up properly after a system reboot?

I confirmed it by running the command manually instead :)