For those who still see this issue in 18.04:
Is the icon really giant (144x144) for you, as attached to this bug; or is it somewhat smaller (48x48), as attached to bug 1765704?
Does installing/removing gnome-icon-theme, as per comment 8, do anything for you?
If you execute xprop from gnome-terminal, then click on gnome-terminal's window, and scroll back, in what size(s) is/are the icon(s) shown there?
For those who still see this issue in 18.04:
Is the icon really giant (144x144) for you, as attached to this bug; or is it somewhat smaller (48x48), as attached to bug 1765704?
Does installing/removing gnome-icon-theme, as per comment 8, do anything for you?
If you execute xprop from gnome-terminal, then click on gnome-terminal's window, and scroll back, in what size(s) is/are the icon(s) shown there?