pyang_plugin: fixed TypeError
pyang_plugin: fixed TypeError

Dipsingh/gobgp,a16/gobgp,YujiOshima/gobgp,osrg/gobgp,h-naoto/gobgp,Dipsingh/gobgp,fujita/gobgp,ishidawataru/gobgp,j-kato/gobgp,osrg/gobgp,fujita/gobgp,YujiOshima/gobgp,a16/gobgp,Dipsingh/gobgp,ishidawataru/gobgp,ramrunner/gobgp,a16/gobgp,YujiOshima/gobgp,j-kato/gobgp,h-naoto/gobgp,tamihiro/gobgp,ramrunner/gobgp,fujita/gobgp,tamihiro/gobgp,fujita/gobgp,a16/gobgp,a16/gobgp,osrg/gobgp,h-naoto/gobgp,a16/gobgp,osrg/gobgp,a16/gobgp,tamihiro/gobgp,postfix/gobgp,ramrunner/gobgp,j-kato/gobgp,postfix/gobgp,ishidawataru/gobgp,tamihiro/gobgp,postfix/gobgp