Reset @rest_height when clear screen

Author: aycabta

lib/reline/line_editor.rb

@@ -813,6 +813,7 @@ def just_move_cursor
     end
     move_cursor_up(back)
     move_cursor_down(@first_line_started_from + @started_from)
+    @rest_height = (Reline::IOGate.get_screen_size.first - 1) - Reline::IOGate.cursor_pos.y
     Reline::IOGate.move_cursor_column((prompt_width + @cursor) % @screen_size.last)
   end
 

test/reline/yamatanooroti/test_rendering.rb

@@ -719,6 +719,17 @@ def test_dynamic_prompt_returns_empty
       EOC
     end
 
+    def test_reset_rest_height_when_clear_screen
+      start_terminal(5, 20, %W{ruby -I#{@pwd}/lib #{@pwd}/test/reline/yamatanooroti/multiline_repl}, startup_message: 'Multiline REPL.')
+      write("\n\n\n\C-l3\n")
+      close
+      assert_screen(<<~EOC)
+        prompt> 3
+        => 3
+        prompt>
+      EOC
+    end
+
     private def write_inputrc(content)
       File.open(@inputrc_file, 'w') do |f|
         f.write content