2nd-voice \stemDown ignored with cross-staff stems

[Javier Ruiz-Alma]

%
%Can't get the 8th notes from 2nd-voice bass to
%get beamed plus retain the default stems down direction
%If I remove the beaming brackets '[' ']', these notes will show stem down 
with flags
%Once beamed, the notes will show stem up, even after applying \stemDown 
command
%How do I force beam plus stemDown in this situation?
%
\version "2.13.60"
\score {
        \new PianoStaff
                <<
                \new Staff \relative c'{
                        <e c>8[ c]
                }
                \new Staff \relative c{
                        <<{
                        \clef bass
                        \autoBeamOff
                        \override Stem #'cross-staff = ##t
                        \override Stem #'length = #10
                        \override Stem #'flag-style = #'no-flag
                        g'8 <a e>
                        \revert Stem #'cross-staff
                        \revert Stem #'length
                        \revert Stem #'flag-style
                        \autoBeamOn
                        }\\
                        {e,[ f] }>>
                }
                >>
                \layout{}
}