I filed a ticket in Cobbler Trac:
https://fedorahosted.org/cobbler/ticket/351

* Problem:

Cobbler reposync downloads the wrong version of packages.

* Cobbler version:

cobbler-1.4.1-1.el5

* OS-version:

CentOS release 5.2 (Final)

* Repo:

cobbler repo report epel-4-x86_64
repo             : epel-4-x86_64
arch             : x86_64
breed            : yum
comment          : 
created          : Sat Jan 10 10:13:07 2009
createrepo_flags : -c cache
environment      : {}
keep updated     : True
mirror           : ftp://ftp.surfnet.nl/pub/os/Linux/distr/fedora-epel/4/x86_64
mirror locally   : True
modified         : Mon Jan 19 18:06:39 2009
owners           : ['admin']
priority         : 99
rpm list         : ['bash-completion', 'nrpe']
yum options      : {}

* RPM-packages on repo-mirror (important: el4 ):

* Output 'cobbler reposync --only=epel-4-x86_64' :

- creating: /var/www/cobbler/repo_mirror/epel-4-x86_64/.origin/epel-4-x86_64.repo
- /usr/bin/yumdownloader --resolve  -c /var/www/cobbler/repo_mirror/epel-4-x86_64/.origin/epel-4-x86_64.repo --destdir=/var/www/cobbler/repo_mirror/epel-4-x86_64 bash-completion nrpe
centos-5.2-x86_64-updates 100% |=========================|  951 B    00:00     
epel-5-x86_64             100% |=========================|  951 B    00:00     
centos-5.2-x86_64-addons  100% |=========================|  951 B    00:00     
tref                      100% |=========================|  951 B    00:00     
core-0                    100% |=========================| 1.1 kB    00:00     
epel-4-x86_64             100% |=========================| 1.1 kB    00:00     
epel-testing-5-x86_64     100% |=========================|  951 B    00:00     
centos-5.2-x86_64-extras  100% |=========================|  951 B    00:00     
--> Running transaction check
---> Package bash-completion.noarch 0:20060301-4.el5 set to be updated
---> Package nrpe.x86_64 0:2.12-3.el5 set to be updated
--> Finished Dependency Resolution
bash-completion-20060301- 100% |=========================| 144 kB    00:00     
nrpe-2.12-3.el5.x86_64.rp 100% |=========================|  32 kB    00:00     
- createrepo -c cache /var/www/cobbler/repo_mirror/epel-4-x86_64
2/2 - nrpe-2.12-3.el5.x86_64.rpm                                                
Saving Primary metadata
Saving file lists metadata
Saving other metadata
- creating: /var/www/cobbler/repo_mirror/epel-4-x86_64/config.repo

* It downloads the el5 versions of 'bash-completion' and 'nrpe' !!! How is this possible?

* If you need more info, please let me know.