replace hardcoded path for 'df' with os:find_executable
replace hardcoded path for 'df' with os:find_executable

isvilen/otp,dumbbell/otp,isvilen/otp,mikpe/otp,getong/otp,dgud/otp,rlipscombe/otp,vladdu/otp,isvilen/otp,jj1bdx/otp,jj1bdx/otp,jj1bdx/otp,ferd/otp,rlipscombe/otp,mikpe/otp,jj1bdx/otp,mikpe/otp,g-andrade/otp,potatosalad/otp,vinoski/otp,uabboli/otp,dgud/otp,vinoski/otp,emacsmirror/erlang,ferd/otp,emacsmirror/erlang,mikpe/otp,isvilen/otp,vladdu/otp,emacsmirror/erlang,jj1bdx/otp,getong/otp,mikpe/otp,isvilen/otp,g-andrade/otp,dumbbell/otp,g-andrade/otp,vinoski/otp,uabboli/otp,isvilen/otp,dumbbell/otp,dumbbell/otp,uabboli/otp,uabboli/otp,vinoski/otp,erlang/otp,erlang/otp,rlipscombe/otp,potatosalad/otp,dgud/otp,rlipscombe/otp,uabboli/otp,dumbbell/otp,emacsmirror/erlang,mikpe/otp,mikpe/otp,vinoski/otp,potatosalad/otp,getong/otp,erlang/otp,jj1bdx/otp,dgud/otp,getong/otp,erlang/otp,emacsmirror/erlang,dumbbell/otp,dgud/otp,bjorng/otp,getong/otp,jj1bdx/otp,jj1bdx/otp,bjorng/otp,bjorng/otp,getong/otp,erlang/otp,vladdu/otp,vladdu/otp,potatosalad/otp,vinoski/otp,dgud/otp,vinoski/otp,uabboli/otp,rlipscombe/otp,g-andrade/otp,potatosalad/otp,ferd/otp,ferd/otp,emacsmirror/erlang,dumbbell/otp,rlipscombe/otp,erlang/otp,g-andrade/otp,ferd/otp,getong/otp,g-andrade/otp,isvilen/otp,mikpe/otp,ferd/otp,isvilen/otp,g-andrade/otp,erlang/otp,emacsmirror/erlang,uabboli/otp,erlang/otp,vladdu/otp,bjorng/otp,bjorng/otp,g-andrade/otp,getong/otp,jj1bdx/otp,vladdu/otp,potatosalad/otp,bjorng/otp,vinoski/otp,emacsmirror/erlang,emacsmirror/erlang,bjorng/otp,emacsmirror/erlang,isvilen/otp,vladdu/otp,potatosalad/otp,vinoski/otp,potatosalad/otp,ferd/otp,uabboli/otp,getong/otp,erlang/otp,rlipscombe/otp,erlang/otp,isvilen/otp,dumbbell/otp,uabboli/otp,jj1bdx/otp,dgud/otp,vladdu/otp,dgud/otp,mikpe/otp,ferd/otp,ferd/otp,rlipscombe/otp,potatosalad/otp,dgud/otp,dumbbell/otp,rlipscombe/otp,bjorng/otp,rlipscombe/otp,g-andrade/otp,bjorng/otp,g-andrade/otp,vinoski/otp,getong/otp,potatosalad/otp,mikpe/otp,bjorng/otp,dumbbell/otp,dgud/otp,vladdu/otp