Erase verf key left from creation from ientries on every modification

src/nfs_kv_setattr.cpp

@@ -71,6 +71,7 @@ resume_1:
         }
         st->new_attrs[kv.first] = kv.second;
     }
+    st->new_attrs.erase("verf");
     st->self->parent->db->set(kv_inode_key(st->ino), json11::Json(st->new_attrs).dump(), [st](int res)
     {
         st->res = res;