PEP 475: on EINTR, retry the function even if the timeout is equals to zero

Retry:

* signal.sigtimedwait()
* threading.Lock.acquire()
* threading.RLock.acquire()
* time.sleep()

Modules/signalmodule.c

@@ -1011,7 +1011,7 @@ signal_sigtimedwait(PyObject *self, PyObject *args)
 
         monotonic = _PyTime_GetMonotonicClock();
         timeout = deadline - monotonic;
-        if (timeout <= 0)
+        if (timeout < 0)
             break;
     } while (1);