policy: avoid crash when getting ext-community
policy: avoid crash when getting ext-community

j-kato/gobgp,a16/gobgp,ishidawataru/gobgp,a16/gobgp,Dipsingh/gobgp,tamihiro/gobgp,Dipsingh/gobgp,fujita/gobgp,osrg/gobgp,osrg/gobgp,j-kato/gobgp,tamihiro/gobgp,a16/gobgp,tamihiro/gobgp,ishidawataru/gobgp,fujita/gobgp,a16/gobgp,ishidawataru/gobgp,a16/gobgp,osrg/gobgp,tamihiro/gobgp,a16/gobgp,a16/gobgp,osrg/gobgp,j-kato/gobgp,fujita/gobgp,fujita/gobgp,Dipsingh/gobgp