Allow calling as_image_set_pixbuf() with a NULL pixbuf
Allow calling as_image_set_pixbuf() with a NULL pixbuf

mitya57/appstream-glib,kalev/appstream-glib,kalev/appstream-glib,ikeydoherty/appstream-glib,ximion/appstream-glib,superm1/appstream-glib,mitya57/appstream-glib,ximion/appstream-glib,hughsie/appstream-glib,ikeydoherty/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib,ximion/appstream-glib,superm1/appstream-glib