don't record an external trait if it's not external

src/librustdoc/clean/inline.rs

@@ -520,6 +520,10 @@ fn separate_supertrait_bounds(mut g: clean::Generics)
 }
 
 pub fn record_extern_trait(cx: &DocContext, did: DefId) {
+    if did.is_local() {
+        return;
+    }
+
     if cx.external_traits.borrow().contains_key(&did) ||
         cx.active_extern_traits.borrow().contains(&did)
     {