Suppose we have the Deferred object and try to set handlers on progress for both .promise() and .then() objects:

var d = $.Deferred().notify();
d.promise().progress(function(){ console.log('promise') });
d.then().progress(function(){ console.log('then') });

This works as expected, both progress handlers will fire. But if we try to set progress handlers for resolved Deferred, the result will be different:

var d = $.Deferred().notify().resolve(); // Look there, I'm resolved.
d.promise().progress(function(){ console.log('promise') });
d.then().progress(function(){ console.log('then') });

Only first handler will fire. The problem in tuples order. Progress tuple come last, and therefor, when newDefer.notify() is called, newDefer is already resolved and doesn't accept notifying.

This bug is similar to #1894, but slightly different.