Although we already ignore "invalid recipient" errors, a new type
of error recently popped: the mail service responds with
> Net::SMTPServerBusy '400 unexpected recipients: want atleast 1, got 0'
We want to also ignore this kind of errors.
As mailers are run asynchronously, they don't have access to the
CurrentConfirmation defined in an earlier request.
For the procedure_after_confirmation to be serialized to the Mailer,
we need to pass it at creation time.
This allows to redirect the user to the procedure they signed up for
even when the browser session is not available (like if they changed
of browser).
Fix#4738
`default template_path:` was the documented way, but wasn’t working
(and there was no hint in the source code of Devise that it could
work)
Therefore, let’s override `template_paths` instead and stop worrying
