Wrong placement of BreathingSign

[Thomas Morley]

With "2.14.2" and "2.15.2" the BreathingSign isn't positioned correct,
while using changed staff-size or (default) TabStaff.
2.12.3-behaviour was accurate.

%\version "2.12.3"
\version "2.14.2"
%\version "2.15.20"

mel = { c'1 \breathe }

\score {
        <<
        \new Staff\with {
                fontSize = #-4
                \override StaffSymbol #'staff-space = #(magstep -4)
                \override StaffSymbol #'thickness = #(magstep -4)
        }
        \mel

        \new Staff
        \mel

        \new TabStaff
        \mel
        >>
}

correct-2-12-3.png
Description: PNG image

wrong-2-14-2.png
Description: PNG image