how to upgrade linux_base?

[eternal]

hello,

	i have linux_base-7.1_5 installed on my freebsd4.9-release box.  i have
been trying to use portupgrade to upgrade a few of the ports that i have
installed, but a few of them require linux_base-7.1_7.  when portupgrade
tries to upgrade linux_base, it returns:
"execution of rpm-4.0.2-8 script failed, exit status 1"

should i just use pkg_deinstall go get rid of the installed _5, and then
manually make and make install _7?

i've seen alot of issues on this from searching on google, but no
answers...  perhaps you maight be able to assist me (us)?

thanks in advance,
shaun