don't destroy package when converting python list to HifPackageSet
don't destroy package when converting python list to HifPackageSet

fixing
1: test_package_in (tests.test_query.TestQuery) ...
1: (process:9959): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
1:
1: (process:9959): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
1: ok

Conan-Kudo/libhif,edynox/libdnf,edynox/libdnf,Conan-Kudo/libhif,rpm-software-management/libdnf,rpm-software-management/libdnf,rpm-software-management/libhif,rpm-software-management/libdnf,edynox/libdnf,hughsie/libhif,rpm-software-management/libhif,edynox/libdnf,rpm-software-management/libdnf,hughsie/libhif,Conan-Kudo/libhif,hughsie/libhif,Conan-Kudo/libhif,rpm-software-management/libhif,rpm-software-management/libhif,hughsie/libhif