core: Fix a minor memory leak
core: Fix a minor memory leak

leandrosansilva/ostree,gatispaeglis/ostree,leandrosansilva/ostree,GNOME/ostree,leandrosansilva/ostree,resin-io/ostree,GNOME/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,resin-io/ostree,gatispaeglis/ostree,resin-io/ostree,sujitfulse/ostree,sujitfulse/ostree,gatispaeglis/ostree,GNOME/ostree,resin-io/ostree,GNOME/ostree,leandrosansilva/ostree,leandrosansilva/ostree,sujitfulse/ostree,sujitfulse/ostree,gatispaeglis/ostree,sujitfulse/ostree,resin-io/ostree