Comment 23 for bug 194140

AIUI, apt is meant to only balk about immediate configuration for packages that are essential or are dependencies of apt. libsasl2-2 is neither in the Ubuntu archive - do you know what modified packages you might have on your system that would cause apt to treat libsasl2-2 as essential?

Anyway, if this were reproducible in the official archive, I think everyone would be seeing it... since they aren't, I'm pretty sure this is a local issue, not a bug in the package. Closing as invalid.

(It happens that this issue should go away for you in the next upload of cyrus-sasl2, because libsasl2-2 will no longer depend on libsasl2-modules. However, the circular dependency is not the bug here.)