cancel `all` or `any` with non cancellable thenables

lib/rsvp/all.js

@@ -12,7 +12,8 @@ function promiseAtLeast(expected_count, promises) {
     for (var i = 0; i < promises.length; i++) {
       promise = promises[i];
 
-      if (promise && typeof promise.then === 'function') {
+      if (promise && typeof promise.then === 'function' &&
+          typeof promise.cancel === 'function') {
         promise.cancel();
       }
     }

test/tests/extension_test.js

@@ -782,6 +782,40 @@ describe("RSVP extensions", function() {
       }, 20);
     });
 
+    specify('cancel with non cancellable thenables', function(done) {
+      var firstResolver, secondResolver;
+
+      var first = new RSVP.Promise(function(resolve, reject) {
+        firstResolver = { resolve: resolve, reject: reject };
+      });
+
+      var second = new RSVP.Promise(function(resolve, reject) {
+        secondResolver = { resolve: resolve, reject: reject };
+      });
+
+      setTimeout(function() {
+        firstResolver.reject({});
+      }, 0);
+
+      setTimeout(function() {
+        secondResolver.resolve(true);
+      }, 5000);
+
+      var all_promise = RSVP.all([{"then": function () {
+        return;
+      }}, first, second]);
+
+      all_promise.cancel();
+
+      setTimeout(function() {
+        assert(first.isRejected);
+        assert(first.rejectedReason instanceof RSVP.CancellationError);
+        assert(second.isRejected);
+        assert(second.rejectedReason instanceof RSVP.CancellationError);
+        done();
+      }, 20);
+    });
+
     specify('notifies promises progress', function(done) {
       var firstResolver, secondResolver, count = 0, expected = {};
 
@@ -992,6 +1026,40 @@ describe("RSVP extensions", function() {
       }, 20);
     });
 
+    specify('cancel with non cancellable thenables', function(done) {
+      var firstResolver, secondResolver;
+
+      var first = new RSVP.Promise(function(resolve, reject) {
+        firstResolver = { resolve: resolve, reject: reject };
+      });
+
+      var second = new RSVP.Promise(function(resolve, reject) {
+        secondResolver = { resolve: resolve, reject: reject };
+      });
+
+      setTimeout(function() {
+        firstResolver.reject({});
+      }, 0);
+
+      setTimeout(function() {
+        secondResolver.resolve(true);
+      }, 5000);
+
+      var all_promise = RSVP.any([{"then": function () {
+        return;
+      }}, first, second]);
+
+      all_promise.cancel();
+
+      setTimeout(function() {
+        assert(first.isRejected);
+        assert(first.rejectedReason instanceof RSVP.CancellationError);
+        assert(second.isRejected);
+        assert(second.rejectedReason instanceof RSVP.CancellationError);
+        done();
+      }, 20);
+    });
+
     specify('notifies promises progress', function(done) {
       var firstResolver, secondResolver, count = 0, expected = {};