ITerm2 prints a null character

Question

Each time the command that I issue from iTerm2 takes more than a minute to complete, the null ^ @ character is printed once every minute or so continuously, until the process completes.

I cannot figure out if this is a bug or a function that I have to somehow disable.

It actually seems like it is being printed on the terminal, but it is not going to either stdout or stderr:

$ echo `sleep 181`
^@^@
$ echo `sleep 181` 2> /tmp/stderr
^@^@
$ echo `sleep 181` > /tmp/stdout
^@^@

Answer 1

Disable "when idle send ascii code" in prefs-> profiles-> session.