This call is useless and wrong, the empty string has a special meaning in Gettext.
"field[0.15,0.075;5.91,1;te_search;;" .. core.formspec_escape(tabdata.search_for) .. "]" ..
"button[5.62,-0.25;1.5,1;btn_mp_search;" .. fgettext("Search") .. "]" ..
"image_button[6.97,-.165;.83,.83;" .. core.formspec_escape(defaulttexturedir .. "refresh.png")
- .. ";btn_mp_refresh;" .. fgettext("") .. "]" ..
+ .. ";btn_mp_refresh;]" ..
-- Address / Port
"label[7.75,-0.25;" .. fgettext("Address / Port") .. "]" ..