I received a private message with this subject:
8.5.6 install en français
I replied to that message.
When I view the list of the inbox messages at https://community.concretecms.com/account/messages
I correctly see the message subject.
But when I see the list of the sent messages at https://community.concretecms.com/account/messages/-2
I read
Re: 8.5.6 install en français
I’m pretty sure that the cause of this is a double call of h()