fingering instructions bug?

[Stan Sanderson]

\version "2.10.20"
\layout {ragged-right = ##t}
sfoL = \set fingeringOrientations = #'(left)
sfoR = \set fingeringOrientations = #'(right)
sfoU = \set fingeringOrientations = #'(up)
sfoD = \set fingeringOrientations = #'(down)

\relative c'' { 
        \sfoR < a-1 d-2>4
        \sfoL < a-1 d-2>
        \sfoU <a-1 d-2>
        \sfoD <a-1 d-2>
%% with slur
        \sfoR < a-1 d-2>(
        \sfoL < a-1 d-2>
        \sfoU <a-1 d-2>
        \sfoD <a-1 d-2>)
}

right fingering orientations are incorrect when a slur is involved.