Untested, but I believe this would work:

diff --git a/command-stubs/list-harddrives-stub b/command-stubs/list-harddrives-stub
index 4025186..25d9eb0 100755
--- a/command-stubs/list-harddrives-stub
+++ b/command-stubs/list-harddrives-stub
@@ -27,7 +27,8 @@ def main(argv):
     lst = set()
 
     for dev in filter(lambda d: d.type != parted.DEVICE_DM, parted.getAllDevices()):
-        lst.add((os.path.basename(dev.path), dev.getSize()))
+        path = dev.path.lstrip("/dev/")
+        lst.add((path, dev.getSize()))
 
     lst = list(lst)
     lst.sort()

In the installation environment, you'd apply that to the list-harddrives script.  It gets renamed during environment composition.

This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has 
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed 
products. This request is not yet committed for inclusion in an Update release.

The change in RC4 (anaconda-13.21.116-1.el6) breaks 'list-harddrives' on s390x:

[anaconda root@rtt6 root]# list-harddrives 
asdb 2347.734375
asdc 2347.734375
asdd 2347.734375

With RC3 (anaconda-13.21.115-1.el6), results are OK:
[anaconda root@rtt6 root]# list-harddrives 
dasdb 2347.734375
dasdc 2347.734375
dasdd 2347.734375

Whole path of the devices:
/dev/dasdb
/dev/dasdc
/dev/dasdd

Moving back to ASSIGNED.

The S390x is also going through certification.

Tested on build RHEL6.1-20110510.1 (RC5.1) with anaconda-13.21.117-1.el6.

On a system with a cciss controller:
sh-4.1# list-harddrives 
cciss/c0d0 114439.21875

on a x86_64 system with ordinary sda drive:
sh-4.1# list-harddrives 
sda 152627.835938

on s390x with one DASD drive:
[anaconda root@rtt6 root]# list-harddrives 
dasdb 9390.9375

x86_64 system running in kvm with one vda drive:
-bash-4.1# list-harddrives 
vda 26624.0


Also tested with a kickstart utilizing the list-harddrives command:

...
%include /partitioning

%pre
#!/bin/bash
INSTALL_DEVICE="$(list-harddrives | cut -d' ' -f1 | head -n 1)"
echo "bootloader --location=mbr --driveorder=$INSTALL_DEVICE --append='console=ttyS0,115200 crashkernel=auto'" > /partitioning
echo "clearpart --all" >> partitioning
echo "part /boot --fstype=ext4 --size=500 --ondisk=$INSTALL_DEVICE" >> /partitioning
echo "part pv.104002 --grow --size=1 --ondisk=$INSTALL_DEVICE" >> /partitioning
echo "volgroup vg_hpbl460cg501 --pesize=4096 pv.104002" >> /partitioning
echo "logvol /home --fstype=ext4 --name=lv_home --vgname=vg_hpbl460cg501 --grow --size=100" >> /partitioning
echo "logvol / --fstype=ext4 --name=lv_root --vgname=vg_hpbl460cg501 --grow --size=1024 --maxsize=51200" >> /partitioning
echo "logvol swap --name=lv_swap --vgname=vg_hpbl460cg501 --grow --size=1024 --maxsize=10048" >> /partitioning
%end

Moving to VERIFIED.

HP verified by Mike Miller.

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2011-0530.html