rbd: we need to get the latest osdmap when pool does not exists

     sometimes when we rename a pool use the rados api,but the osdmap
     does not update when we use pool_exists api.so we need to get the
     latest osdmap when the pool does not exists, it may exists in the
     newer osdmap.

Signed-off-by:song baisen <song.baisen@zte.com.cn>

src/pybind/rados/rados.pyx

@@ -889,6 +889,13 @@ Rados object in state %s." % self.state)
         if ret >= 0:
             return int(ret)
         elif ret == -errno.ENOENT:
+            rev = self.wait_for_latest_osdmap() 
+            if rev < 0:
+                return None
+            with nogil:
+                ret = rados_pool_lookup(self.cluster, _pool_name)
+            if ret >= 0:
+                return int(ret) 
             return None
         else:
             raise make_ex(ret, "error looking up pool '%s'" % pool_name)