Bug#442645: exim4: newer BDB

[Florian Weimer]

* Marc Haber:

>> Berkeley DB upgrades change the API (in addition to the ABI), so
>> explicitly versioned dependencies (libdb4.6-dev et al.) are better.
>
> So, package maintainers need to be aware which Berkeley DB is
> recommended to be used for appropriate dependencies.

Exactly, just like Curl, OpenSSL, GNUTLS, and so on.

> I have been informed that it is not always a brilliant idea to use
> latest Berkeley DB, right?

If you use on-disk database environments (grep for DB_ENV to get an
idea if this is the case), you need quite a bit of code to handle
updates properly (and downgrades, of course).  If you use just plain
DB objects, it's not very likely that you'll notice any changes.