System doesn't update when there are third party repositories configured on the server.

Issue

• System does not update via yum:

# /usr/sbin/rhn_check

Loaded plugins: rhnplugin
Repository `custom_repo` is missing name in configuration, using id

# /usr/sbin/rhnsd
/usr/sbin/rhnsd: already running

# yum update
Loaded plugins: rhnplugin, security
Repository `custom_repo` is missing name in configuration, using id
Skipping security plugin, no data
Setting up Update Process
No Packages marked for Update

yum search httpd
Loaded plugins: product-id, rhnplugin, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
This system is receiving updates from RHN Classic or RHN Satellite.
RHEL-Repository                                          | 3.6 kB     00:00 ... 
RHEL-Repository/primary_db                               | 2.8 MB     00:00 ... 
epel/metalink                                            |  29 kB     00:00     
epel                                                     | 4.2 kB     00:00     
epel/primary_db                                                                                                                       | 4.0 MB     03:57     
http://public-yum.oracle.com/repo/OracleLinux/OL6/UEK/latest/ppc64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"

[root@example]# yum check-update
Loaded plugins: product-id, refresh-packagekit, security, subscription-manager unexpected eof
http://public-repo.example.com/HDP/centos6/2.x/updates/2.0.6.1/repodata/repomd.xml: [Errno 14] PYCURL ERROR 52 - "Empty reply from server"
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: HDP-2.0.  6. Please verify its path and try again
[root@example]# yum update
Loaded plugins: product-id, refresh-packagekit, security, subscription-manager unexpected eof
http://public-repo.example.com/HDP/centos6/2.x/updates/2.0.6.1/repodata/repomd.xml: [Errno 14] PYCURL ERROR 52 - "Empty reply from server"
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: HDP-2.0.     
  6. Please verify its path and try again