Description of problem:

When you use virt-sysprep on a pre-systemd guest (eg. RHEL 6 guest),
with the --firstboot option, it writes a start-up script called

/etc/rc.d/rc3.d/99virt-sysprep-firstboot

This is of course wrong.  The file should be called

/etc/rc.d/rc3.d/S99virt-sysprep-firstboot
                ^NB

As a result of the incorrect name, the firstboot script does not run.

Version-Release number of selected component (if applicable):

libguestfs 1.20.9, 1.22.4, 1.23.10

Note I have fixed this upstream already:
https://github.com/libguestfs/libguestfs/commit/44c5026d9e06cf5f01098608ddd0aa4acb7bb6eb
This bug exists so that I can check the fix goes into RHEL 6 & RHEL 7.

How reproducible:

100%

Steps to Reproduce:

Create a small shell script that "does something useful".  eg.
It could touch a file at a known location.

export LIBGUESTFS_TRACE=1
virt-sysprep --firstboot ./some-script.sh -a RHEL6.guest
Try to boot the guest.

Observe whether or not the firstboot script ran when the
guest booted (eg. was the file touched?)

Additional info:

The bug was found by Nick Strugnell.