restrainOpenStrings

[BB]

I wonder that
\set TabStaff.restrainOpenStrings = ##t
is not enough to really avoid open strings?
It only works together with
\set TabStaff.minimumFret = #1

I can live with this need of this aditional line, but I find the logik 
is questionable. Is that done by will?

Regards

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\version "2.19.25"

#(set-global-staff-size 22)

be-bass = \stringTuning <b,, e, a, d  >

BB-Bass = {
\key g \major
\clef bass
\relative c'
{
g,4 d  d' a |
\bar ":|."
}
}

\score {
  <<
      \new Staff {
        \BB-Bass
      }
      \new TabStaff {
      \tabFullNotation
      \set TabStaff.stringTunings = #be-bass
      %\set TabStaff.minimumFret = #1
      \set TabStaff.restrainOpenStrings = ##t
      \BB-Bass
      }
  >>
}