If in the kickstart rpm list, the X-windows rpms are not
selected, then you are unable to install any extra rpms in
the kickstart post install section.

This is caused by the rpm database being opened, in the
setupXfree function in doit.c, before the check is made for
the installation of X.  If X is not installed, the function
returns, without closing the rpm database.  The rpm db is
now locked for the remainder of the install process.

If the 'check for X' and 'open rpm db' code blocks are
swapped, the function runs without any problems.