Line is corrupted when pasting long string in vi mode with exit_attribute_mode prompt

[Jack Pearson]

To reproduce:

- Launch a bash shell in a terminal emulator (I've tested konsole and 
gnome-terminal on KDE 5.23.4 with X11, if that matters).

- Copy "Lorem ipsum dolor sit amet, consectetur adipiscing elit" 
(without the quotes) to your clipboard.

- Run these commands in the terminal:

  ```
  bash --norc --noprofile
  set -o vi
  PS1='$(tput sgr0)' # emit exit_attribute_mode capability string
  ```

- Press Ctrl-Shift-V to paste lipsum text into the terminal

- Press Esc

Observe that first six characters of the pasted string have been 
duplicated. If you try to delete them you'll notice you're unable to. 
They're in the same state as the characters that comprise the prompt, 
whatever state that is.

Occasionally I've been able to delete the duplicated characters in 
gnome-terminal.

I've noticed that the length of the string matters. Moderately short 
strings don't cause this issue. If you're unable to reproduce, maybe try 
a longer string.

GNU bash, version 5.1.12(1)-release (x86_64-pc-linux-gnu)



Thanks for all the great work you guys do,

Jack