The patches pushed recently from the upstream fixes this. See
https://gitlab.gnome.org/Jehan/glib/commit/8519368c0eb26ce353e5e1ffd4d23fe8353848dc
- Bug#908705: g_icon_to_string output includes some garbag... Eduard Bloch
- Bug#908705: g_icon_to_string output includes some g... Philip Withnall
- Bug#908705: g_icon_to_string output includes some g... Jeremy Bicha
- Bug#908705: Damián Barberón
- Bug#908705: g_icon_to_string output includes so... Simon McVittie
