session: fix rpc_send_ly dnode free function

When rpc_send_ly is called more that 255 times in the same session, it
fails, because the context has been acquired too many times.

The new_dnode function can not be used for rpc_send_ly because it does
not free the output node, it only frees output.tree. Use a mechanism
similar to get_data_ly, i.e free the output node returned by
sr_rpc_send_tree, call sr_release_data on it as well, and release the
context that was used by our new dnode.

Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>

Author: samuel-gauthier

sysrepo/session.py

@@ -1472,7 +1472,17 @@ def rpc_send_ly(
         if not sr_data_p[0]:
             raise SysrepoInternalError("sr_rpc_send_tree returned NULL")
 
-        return self.new_dnode(sr_data_p[0].tree)
+        ctx = self.acquire_context()
+        dnode = libyang.DNode.new(ctx, sr_data_p[0].tree)
+
+        # customize the free method to use the sysrepo free
+        def sysrepo_free(dnode_src):
+            lib.sr_release_data(sr_data_p[0])
+            self.release_context()
+
+        dnode.free_func = sysrepo_free
+
+        return dnode
 
     def rpc_send(
         self,