Fix printing of error message in add_cmdline_package (RhBug:1455066)
Fix printing of error message in add_cmdline_package (RhBug:1455066)

Object "tmp_py_str" was freed and then used ("fn" depends on "tmp_py_str").

Closes: #290
Approved by: ignatenkobrain

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