Promise dispatch methods cause duplicate unhandled rejections

[SLaks]

var Q = require("q");

var promise = Q.reject(new Error("Test Error!"));

promise
    .invoke("someMethod")
    .fail(function (err) { console.log("Swallowed promise failure", err); });

This prints

Swallowed promise failure [Error: Test Error!]
Unhandled rejection reason: Error: Test Error!
    at Object.<anonymous> (.../q-test.js:3:24)
    at node.js:901:3
From previous event:
    at Object.<anonymous> (.../q-test.js:6:3)

Since .fail() handles the rejection, there shouldn't be an unhandled rejection.

Removing .invoke() (or replacing it with the equivalent .then(function (o) { return o.someMethod(); })) fixes it.

[domenic]

Yeah, dupe of the unfortunate #238. We want this fixed badly; if you have any ideas let us know!

[SLaks]

This happens because fallback() (https://github.com/kriskowal/q/blob/master/q.js#L788) doesn't remove the previous rejection from unhandledRejections.

[domenic]

Woah, OK, nice find! I'll try to turn that into a patch tonight or tomorrow. Maybe I'll implement #265 as well in order to be able to test it nicely.

[SLaks]

Fixed by #290