Clear garbage references twice before starting tests

Clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code
coverage turned on (`vendor/bin/phpunit --coverage-text`).

Author: clue

.travis.yml

@@ -18,7 +18,6 @@ install:
   - composer install
 
 script:
-  - ./vendor/bin/phpunit -v
   - ./vendor/bin/phpunit -v --coverage-text --coverage-clover=./build/logs/clover.xml
 
 after_script:

tests/DeferredTest.php

@@ -23,10 +23,6 @@ public function getPromiseTestAdapter(callable $canceller = null)
     /** @test */
     public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerRejectsWithException()
     {
-        if ($this->getTestResultObject()->getCollectCodeCoverageInformation() === true) {
-            $this->markTestSkipped('This test has memory leaks when code coverage is collected');
-        }
-
         gc_collect_cycles();
         $deferred = new Deferred(function ($resolve, $reject) {
             $reject(new \Exception('foo'));
@@ -40,11 +36,9 @@ public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerRejectsWithEx
     /** @test */
     public function shouldRejectWithoutCreatingGarbageCyclesIfParentCancellerRejectsWithException()
     {
-        if ($this->getTestResultObject()->getCollectCodeCoverageInformation() === true) {
-            $this->markTestSkipped('This test has memory leaks when code coverage is collected');
-        }
-
         gc_collect_cycles();
+        gc_collect_cycles(); // clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code coverage turned on
+
         $deferred = new Deferred(function ($resolve, $reject) {
             $reject(new \Exception('foo'));
         });
@@ -57,11 +51,9 @@ public function shouldRejectWithoutCreatingGarbageCyclesIfParentCancellerRejects
     /** @test */
     public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerHoldsReferenceAndExplicitlyRejectWithException()
     {
-        if ($this->getTestResultObject()->getCollectCodeCoverageInformation() === true) {
-            $this->markTestSkipped('This test has memory leaks when code coverage is collected');
-        }
-
         gc_collect_cycles();
+        gc_collect_cycles(); // clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code coverage turned on
+
         $deferred = new Deferred(function () use (&$deferred) { });
         $deferred->reject(new \Exception('foo'));
         unset($deferred);