Comment 2 for bug 1358717

StacktraceTop:
 wl_log (fmt=fmt@entry=0x7fb059c5bc80 "error: XDG_RUNTIME_DIR not set in the environment.\n") at ../src/wayland-util.c:378
 connect_to_socket (name=0x0) at ../src/wayland-client.c:638
 wl_display_connect (name=name@entry=0x0) at ../src/wayland-client.c:775
 _gdk_wayland_display_open (display_name=0x0) at /build/buildd/gtk+3.0-3.12.2/./gdk/wayland/gdkdisplay-wayland.c:249
 gdk_display_manager_open_display (manager=<optimized out>, name=0x0) at /build/buildd/gtk+3.0-3.12.2/./gdk/gdkdisplaymanager.c:462