Respect \r in individual stdout results

lib/livebook/session/data.ex

@@ -854,6 +854,8 @@ defmodule Livebook.Session.Data do
     )
   end
 
+  defp add_output([], output) when is_binary(output), do: [apply_rewind(output)]
+
   defp add_output([], output), do: [output]
 
   defp add_output([head | tail], output) when is_binary(head) and is_binary(output) do

test/livebook/session/data_test.exs

@@ -1814,6 +1814,29 @@ defmodule Livebook.Session.DataTest do
               }, []} = Data.apply_operation(data, operation)
     end
 
+    test "normalizes individual stdout results to respect CR" do
+      data =
+        data_after_operations!([
+          {:insert_section, self(), 0, "s1"},
+          {:insert_cell, self(), "s1", 0, :elixir, "c1"},
+          {:set_runtime, self(), NoopRuntime.new()},
+          {:queue_cells_evaluation, self(), ["c1"]}
+        ])
+
+      operation = {:add_cell_evaluation_output, self(), "c1", "Hola\rHey"}
+
+      assert {:ok,
+              %{
+                notebook: %{
+                  sections: [
+                    %{
+                      cells: [%{outputs: ["Hey"]}]
+                    }
+                  ]
+                }
+              }, []} = Data.apply_operation(data, operation)
+    end
+
     test "normalizes consecutive stdout results to respect CR" do
       data =
         data_after_operations!([