Bash spews bracketed-paste escape sequences when handling signal.

[Kaz Kylheku]

Hi! 

I first ran into this issue on MacOS using the Homebrew build of Bash 5 
(BASH_VERSION "5.2.37(1)-release").

When a trap is installed for a signal, and delivered, Bash sends characters to 
the terminal which move the cursor.

Steps to repro: 

1. Register the simplest possible trap for the SIGALRM signal:

     trap : ALRM 

2. In the background, start a loop which delivers the signal to the shell

     while sleep 1; do kill -ALRM $$ ; done &

3. Every time the signal is delivered, observe Bash spewing the escape 
sequences for disabling and enabling
   bracketed paste, with a carriage return in between them that moves the 
cursor.
   (One way to capture the output is to do the above steps under the "script" 
command; then
   find the characters in the typescript transcript file.)

If you do not have "trap : ALRM" then this doesn't happen.

The expected behavior is that no output should be produced. Bash should just 
handle
the signal and execute the trap without TTY interaction.

See this question on the "Ask Different" Stack Exchange site:

https://apple.stackexchange.com/questions/477385/why-am-i-having-an-issue-with-restoring-cursor-position-when-using-basta-on-maco

Cheers ...