message: Teach coverity that read_size is never zero
diff: @@ -502,7 +502,7 @@ TEST_CASE("mongocxx::gridfs::downloader::read with arbitrary sizes", "[gridfs::d
  std::int64_t file_length = 100;
  std::int32_t chunk_size = 9;
  - std::int32_t read_size;
  + std::int32_t read_size = 0;
  SECTION("read_size = 1") {
  read_size = 1;
  @@ -532,6 +532,8 @@ TEST_CASE("mongocxx::gridfs::downloader::read with arbitrary sizes", "[gridfs::d
  read_size = static_cast<std::int32_t>(file_length + 1);
  }
  + REQUIRE(read_size != 0);
  +
  bsoncxx::types::value id{bsoncxx::types::b_oid{bsoncxx::oid{}}};
  std::vector<std::uint8_t> expected = manual_gridfs_initialize(db, file_length, chunk_size, id);
  