Description:
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Somehow runTasks()  conflicts with knowing it couldn't 
connect from a previous call to runTasks()

Reproduce code:
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$a = new GearmanClient();
$a->addServer('192.168.0.131');
$a->addTask('test', 'data');
$a->runTasks();
PHP Warning:  GearmanClient::runTasks(): gearman_connection_flush:could not connect in php shell code on line 1
// run runTasks again,
$a->runTasks();


Expected result:
----------------
same PHP warning

Actual result:
--------------
Segmentation fault