phab-refresh: do not error out when the stack is empty
Actually, empty stack is easier to get than I expected (and harmless). When a
stack is publish, heptapod will detect the even, empty the stack (triggering CI)
and "forgetting" the branch afterward.
So we stop returning as error in this case.
Differential Revision: https://phab.mercurial-scm.org/D9513
{
// 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)
}