Try to get this test to be more stable:

Try to get this test to be more stable:
 * disable gc during the test run because we are spawning objects and there
   was an exception when calling Popen.__del__
 * Always set an alarm handler so the process doesn't exit if the test fails
   (should probably add assertions on the value of hndl_called in more places)
 * Using a negative time causes Linux to treat it as zero, so disable that test.