Set this test as slow

tests/Composer/Test/Util/RemoteFilesystemTest.php

@@ -137,6 +137,9 @@ class RemoteFilesystemTest extends \PHPUnit_Framework_TestCase
         $this->assertNull($this->callCallbackGet($fs, STREAM_NOTIFY_FAILURE, 0, 'HTTP/1.1 404 Not Found', 404, 0, 0));
     }
 
+    /**
+     * @group slow
+     */
     public function testCaptureAuthenticationParamsFromUrl()
     {
         $io = $this->getMock('Composer\IO\IOInterface');