Error mail from daily_task.sh

hello.

I got the mail below from my box, just after a bunch of certificate were succesfully renewed. (and some were not since “The certificate is valid for at least another 30 days — no need to replace”.)
Everything seem to be in order,
Status page is all green (except that I am still on 0.21b), mail are going in and out.

Any idea what may be wrong ?

Thanks.

Cron root@box (cd /root/mailinabox && management/daily_tasks.sh)

Exception ignored in: <bound method ClientNetwork.del of <acme.client.ClientNetwork object at 0x7f761af06518>>
Traceback (most recent call last):
File “/usr/local/lib/python3.4/dist-packages/acme/client.py”, line 511, in del
self.session.close()
File “/usr/local/lib/python3.4/dist-packages/requests/sessions.py”, line 676, in close
for v in self.adapters.values():
File “/usr/lib/python3.4/_collections_abc.py”, line 512, in iter
for key in self._mapping:
File “/usr/lib/python3.4/collections/init.py”, line 91, in iter
curr = root.next
ReferenceError: weakly-referenced object no longer exists