I cam across this error when running anything with rpm:

rpmdb: fatal region error detected; run recovery
error: db4 error(-30982) from dbenv->open: DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index

It comes from a lock file and some old datbase files that have been left over. Just clear out the /var/lib/rpm directory, rebuild rpm and it should work fine.

#cd /var/lib/rpm
#rm -f /var/lib/rpm/__db*
#rpm --rebuilddb