RPM limitations at kickstart time?

[Hal Wine]

with rpm 4.2.3-10 (RHEL 3 ES update 3), I'm seeing rpm database
corruption when having an RPM install another RPM in a %post scriptlet
during kickstart.

Supposedly, this is permitted since 4.1-1, and it works fine outside of
kickstart (anaconda).

rpm at kickstart time claims to support the feature (as advertised via
examination of 'rpm --showrc' output).

Any pointers to solutions? Or documentation of the limitations at
kickstart time?

Thanks,
--Hal

P.S. Yes, I have my reasons for doing this.