tests: remove flakiness in test-nointerrupt.t
The problem was that the reaction to the signal was racing against
the completion of the command.
Since reaction to the signal is to print a line of warning,
we can fix this by waiting for that warning to appear before
allowing the command to complete.
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}