Remove a dict.has_key() use to silence a warning when running under -3.

Lib/asyncore.py

@@ -267,7 +267,7 @@ class dispatcher:
         fd = self._fileno
         if map is None:
             map = self._map
-        if map.has_key(fd):
+        if fd in map:
             #self.log_info('closing channel %d:%s' % (fd, self))
             del map[fd]
         self._fileno = None