367.xx: leaves a zombie sddm-greeter process behind

as the topic says: when I disable sddm while it shows its greeter (i.e. systemctl stop sddm from a tty), it leaves behind a zombie sddm-greeter process, but only when the nvidia driver is used. With the intel gfx driver the greeter terminates properly (qt-5.6.x, sddm-0.13, X Server 1.18.3, mesa git head for intel, glibc-2.23)

EDIT: I’ve gained access to a radeon-based machine, which also doesn’t suffer this “bug” (mesa and xorg git heads, plus qt-5.6, sddm-0.13).