Maillog error - warn: Unescaped left brace in regex is deprecated here (and will be fata))

[Paul Schmehl]

I'm seeing this error in the logs:

warn: Unescaped left brace in regex is deprecated here (and will be fata))
It comes right after this:

status=sent (delivered via filter service

The filter service uses filter.sh (stolen from the docs) and spamassassin. 
Is it safe to assume this is a code problem in spam assassin (which I 
assume they will fix at some point)?

Googling says it's a perl error, so it can't be the filter shell script.

Paul Schmehl
Independent Researcher