py3: add extra traceback line present on Python 3.8
I'm not sure why Python 3.8 is outputting this line. It
appears to be a change in behavior of formatting tracebacks on
Python 3.8. So let's add it to expected output.
With this change, test-hook.t now passes on Python 3.8.
Differential Revision: https://phab.mercurial-scm.org/D7946
{
// 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)
}