Comment 3 for bug 130636

What is happening here is this:

 * sudo & runs sudo as a background process. The shell and
   sudo race to each print their prompt.
 * sudo tries to read the password from the terminal. At
   this point it receives a SIGTSTP from the kernel tty subsystem
   due to the terminal having the ttin flag set (ie, issue TSTP on
   terminal input attempt by background process group).
 * if you're lucky your shell will print a message about this
   immediately, but this is not guaranteed. And in any case it is
   confusing.

The solution is that sudo ought to make a non-blocking read of its
terminal _before_ printing the prompt. Then, sudo would get SIGTSTP
straight away and you'd see this:

ian@anarres:~ $ sudo bash &
[1] 7745
ian@anarres:~ $

[1]+ Stopped sudo bash
ian@anarres:~ $

This change ought to be made in whatever library sudo is using for
password prompting.

Ian.