For those of you using Dovecot on Fedora, the noisy syslog is fixed:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=124979

I'd suggest getting the pam SRPM from Rawhide (Fedora development tree) and rebuilding, to minimize dependency issues.

(I haven't tried this yet. I'm just forwarding the bug-closing report.)