More display errors outside scroll region

[ethorondil]

Describe the bug
A similar issue to #3090 holds for ich, where text outside the scroll region isn't updated properly. (In this case, it isn't shifted right.)

To Reproduce
Steps to reproduce the behavior:

1. Open a new kitty terminal
2. Cat the file
   bad-sequence2.txt

Expected behavior
$ cat bad-sequence2.txt

YXX
$

Actual behavior
$ cat bad-sequence2.txt

YX
$

Environment details
OS: Name and version of operating system(s)

Linux desktop 5.8.0-3-amd64 #1 SMP Debian 5.8.14-1 (2020-10-10) x86_64
Debian GNU/Linux bullseye/sid \n \l
Loaded config files: /etc/xdg/kitty/kitty.conf, /home/ecprice/.config/kitty/kitty.conf
Running under: X11

Config options different from defaults:
close_on_child_death  True
enable_audio_bell     False
font_size             16.0
initial_window_height (24, 'cells')
initial_window_width  (80, 'cells')
remember_window_size  False
update_check_interval 0.0
Added shortcuts:
	shift+page_up KeyAction(func='scroll_page_up', args=())
	shift+page_down KeyAction(func='scroll_page_down', args=())
	control+l KeyAction(func='combine', args=(KeyAction(func='clear_terminal', args=['scroll', True]), KeyAction(func='send_text', args=['normal,application', b'\x0c'])))