Broken piano template w/ centered dynamics

[Hinrik ÖrnSigurðsson]

http://lilypond.org/doc/v2.12/input/lsr/lilypond-snippets/Expressive-marks#Piano-template-with-centered-dynamics

If one sets an instrument name (\set PianoStaff.instrumentName = #"Piano") with
this template, the name with be incorrectly placed on the Y-axis (below center,
see http://i.imgur.com/SmUDr.png). This only happens if pedaling instructions
are specified, and it seems to relate to the following line:

    \override VerticalAxisGroup #'minimum-Y-extent = #'(-1 . 1)

If it is omitted, the instrument name will be centered, but of course the
dynamics and pedaling will then appear in the wrong place, so this is not a
solution.

The following will move the instrument name slightly closer to the center:

    \override PianoStaff.InstrumentName #'self-alignment-Y = #DOWN

It's still not in the center, though.