fix get_str() in packagedelta-py
fix get_str() in packagedelta-py

rpm-software-management/hawkey,megaumi/hawkey,MichaelMraka/hawkey,jsilhan/hawkey,Conan-Kudo/hawkey,ignatenkobrain/hawkey,cgwalters/hawkey,yavor-atanasov/hawkey,jsilhan/hawkey,megaumi/hawkey,rpm-software-management/hawkey,cgwalters/hawkey,rholy/hawkey,MichaelMraka/hawkey,rpm-software-management/hawkey,mizdebsk/hawkey,rpm-software-management/hawkey,rholy/hawkey,megaumi/hawkey,mizdebsk/hawkey,mizdebsk/hawkey,mizdebsk/hawkey,yavor-atanasov/hawkey,mluscon/hawkey,Conan-Kudo/hawkey,yavor-atanasov/hawkey,Conan-Kudo/hawkey,yavor-atanasov/hawkey,cgwalters/hawkey,mluscon/hawkey,Conan-Kudo/hawkey,ignatenkobrain/hawkey,MichaelMraka/hawkey,cgwalters/hawkey,jsilhan/hawkey,MichaelMraka/hawkey,ignatenkobrain/hawkey,rholy/hawkey,jsilhan/hawkey,ignatenkobrain/hawkey,megaumi/hawkey,mluscon/hawkey,rholy/hawkey,mluscon/hawkey