On a system where /home is in an automount map, rpm won't upgrade a package with autofs running. It fails with a "foo needs (some number)k of space on /home". This is very reproducable with both the version of rpm that is included with Red Hat 6, and the latest update rpm as of yesterday (8/4/99).
Rpm has a concept of net shared path so that a file is installed only on the server, not the clients. You can configure netshared paths by adding (usuallly to /etc/rpm/macros) a line like %_netsharedpath /home:/somewhereelse:/this/is/file and reinstalling (ising --force if necessary) the package on the client so that the files in /home will not be installed. Otherwise, if you want to manage files with rpm that are installed on an NFS mount, you will need root access to that mount point. Is it lack of root access that is the problem? Please reopen this bug if there is some other problem.