4.8.1 -> 4.9.1.3 upgrade woes

[Dash Four]

On one of my development machines (FC13-based) I tried to upgrade my rpm 
from 4.8.1 to 4.9.1.3 yesterday since I couldn't use the existing rpm 
when trying to build images based on newer repositories (FC17+), which 
uses rpm 4.9 and above.

The upgrade wasn't as straight-forward as I thought and I had to build 
the new rpm (4.9.1.3) from sources while upgrading my db4-* packages to 
libdb-devel-5.0, libdb-5.0 and libdb-cxx-5.0 prior to that in order to 
accommodate existing (BuildRequires) dependencies. All seemed well and I 
was able to build the new rpm without too much fuss (though I hit a few 
problems - see at the end of this post).

There was no problem during the actual upgrade either, however, I hit a 
major snag when I tried to use the new rpm.

After the rpm upgrade when I tried to use it (typed "rpm -qa") I've got 
the following errors:

error: db5 error(-30969) from dbenv->open: DB_VERSION_MISMATCH: Database 
environment version mismatch
error: cannot open Packages index using db5 -  (-30969)
error: cannot open Packages database in /var/lib/rpm
error: db5 error(-30969) from dbenv->open: DB_VERSION_MISMATCH: Database 
environment version mismatch
error: cannot open Packages database in /var/lib/rpm

Trying "rpm --rebuilddb -v" wasn't of any use either as I ended up with 
the following errors:

error: db5 error(-30969) from dbenv->open: DB_VERSION_MISMATCH: Database 
environment version mismatch
error: cannot open Packages index using db5 -  (-30969)

Any ideas how to solve this as I am currently unable to use my system to 
add/update/delete packages at all, also which means I cannot revert to 
the old rpm? Thanks in advance for any help!

On a slightly separate note, during the new build, I failed about 32 rpm 
checks - all caused by non-existing "/proc" directory (I am using mock, 
so /proc isn't there, obviously), so that is something for the 
developers to note for future releases.