[noa@localhost rpm]$ rpm -q rpmdb-redhat
rpmdb-redhat-7.0.90-0.20010126

[noa@localhost rpm]$ rpm --redhatprovides foobar
error: cannot open Packages index using db3 - No such file or directory (2)

a strace reveals that rpm seems to ignore the *.rpm files in
/usr/lib/rpmdb/i386-redhat-linux/redhat/ (old format) and instead trying to
open Packages (new format) which isn't there.

open("/usr/lib/rpmdb/i386-redhat-linux/redhat/Packages", O_RDONLY) = -1
ENOENT (No such file or directory)

so the rpmdb-redhat package should be updated to use the new db format
(and a component for the rpmdb-redhat package should be added to bugzilla)