tp_capabilities_supports_tubes_common: check that the self pointer is actually a TpCapabilities
tp_capabilities_supports_tubes_common: check that the self pointer is actually a TpCapabilities

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib