core: make try/catch logic a little clearer in Latch.get()

mitogen/core.py

@@ -1131,21 +1131,21 @@ class Latch(object):
         finally:
             self._lock.release()
 
-        return self._get_sleep(timeout, block, rsock, wsock)
+        poller = self.poller_class()
+        poller.start_receive(rsock.fileno())
+        try:
+            return self._get_sleep(poller, timeout, block, rsock, wsock)
+        finally:
+            poller.close()
 
-    def _get_sleep(self, timeout, block, rsock, wsock):
+    def _get_sleep(self, poller, timeout, block, rsock, wsock):
         _vv and IOLOG.debug('%r._get_sleep(timeout=%r, block=%r)',
                             self, timeout, block)
         e = None
-        poller = self.poller_class()
-        poller.start_receive(rsock.fileno())
-        try:
         try:
             list(poller.poll(timeout))
         except Exception:
             e = sys.exc_info()[1]
-        finally:
-            poller.close()
 
         self._lock.acquire()
         try: