Description of problem:
Packages from a repo can be seen even on a channel where the repo is not assigned to it.


Version-Release number of selected component (if applicable): 2.3


How reproducible: Always


Steps to Reproduce:
1. Create the following channel and child channels
   CentOS6 x86_64
   ├─CentOS6 Base x86_64
   └─CentOS6 Updates x86_64
2. Create the repo "CentOS6 Base x86_64" with repository URL "http://mirror.centos.org/centos/6/os/x86_64/"
3. Go to "Channels" > "Manage software channels" > "CentOS6 Base x86_64" > "Repositories" > check "CentOS6 Base x86_64" and click "Update Repositories" > Click the "Sync" tab > Click "Sync Now"
4. Wait for a few minutes for some of the packages to be synced.
5. Go to "Channels" > "Manage software channels" > "CentOS6 Update x86_64" > "Packages" > "Add"


Actual results:
You can now see the packages for repo "CentOS6 Base x86_64" in channel "CentOS6 Update x86_64" even when that channel does not have any repos assigned to it.

Expected results:
Only see packages for repos assigned to a channel.