If the lbfgsb bundled with python-scipy is replaced with a separate package, the latter should receive something like the following patch, which is included in the SciPy-bundled version of lbfgsb per https://github.com/scipy/scipy/issues/2261
(Synopsis: There are a few places in the lbfgsb code where the no-printing flag is ignored.)
--- a/lbfgsb.f +++ b/lbfgsb.f @@ -2550,7 +2550,9 @@ if (gd .ge. zero) then c the directional derivative >=0. c Line search is impossible. - write(6,*)' ascent direction in projection gd = ', gd + if (iprint .ge. 0) then + write(6,*)' ascent direction in projection gd = ', gd + endif info = -4 return endif @@ -3279,8 +3281,10 @@ 55 continue if ( dd_p .gt.zero ) then call dcopy( n, xp, 1, x, 1 ) - write(6,*) ' Positive dir derivative in projection ' - write(6,*) ' Using the backtracking step ' + if (iprint .ge. 0) then + write(6,*) ' Positive dir derivative in projection ' + write(6,*) ' Using the backtracking step ' + endif else go to 911 endif