Description of problem:
Satellite does not support metadata with the XZ compression. Many  repositories has this type of metadata and satellite is not able to sync it. 

This bug is blocker or complication for testing of ARCH features.

Version-Release number of selected component (if applicable):
Satellite-5.7.0-RHEL6-re20141015.0

How reproducible:
100%

Steps to Reproduce:
#!/usr/bin/python
import xmlrpclib

SATELLITE_URL = "http://localhost/rpc/api"
SATELLITE_LOGIN = "admin"
SATELLITE_PASSWORD = "xxx"

client = xmlrpclib.Server(SATELLITE_URL, verbose=0)
key = client.auth.login(SATELLITE_LOGIN, SATELLITE_PASSWORD)

client.channel.software.createRepo(key, 'rep-fedora-21-aarch64', 'YUM', 'http://mirrors.nic.cz/fedora-secondary/development/21/aarch64/os/')
client.channel.software.addRepoFilter(key, 'rep-fedora-21-aarch64', {'filter': 'kernel*', 'flag': '+'})
client.channel.software.create(key, 'fedora-21-aarch64', 'Fedora 21 (aarch64)', 'XXX', 'channel-aarch64', '')
client.channel.software.associateRepo(key, 'fedora-21-aarch64', 'rep-fedora-21-aarch64')
client.channel.software.syncRepo(key, 'fedora-21-aarch64')


Actual results:
/var/log/rhn/reposync/fedora-21-aarch64.log
Sync started: Thu Oct 16 12:31:25 2014
['/usr/bin/spacewalk-repo-sync', '--channel', 'fedora-21-aarch64', '--type', 'yum', '']
Repo URL: http://mirrors.nic.cz/fedora-secondary/development/21/aarch64/os/
ERROR: xz compression not available
Sync completed.
Total time: 0:00:14



Expected results:
The channel will able to synchronize

Additional info: