Sorry for almost being 0day about it, but a bugfix for imap_zlib segfaults is in this release. Rename worked for me.
There you go: +*dovecot-2.2.8 (21 Nov 2013) + + 21 Nov 2013; Eray Aslan <eras@gentoo.org> +dovecot-2.2.8.ebuild, + +files/dovecot-2.2.8-mail-headers.patch, +files/dovecot-2.2.8-sieve.patch: + Version bump - bug #491832 +