Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1097683
Description of problem:
When trying to create/associate an LDAP source that has the name "Internal", user is told that the name "has already been taken" -- this despite perhaps never having set up an LDAP source before at all.

Version-Release number of selected component (if applicable):
Satellite-6.0.3-RHEL-6-20140508.1

How reproducible:

Steps to Reproduce:
1. Attempt to create a new LDAP source. Give this source the name "Internal"
2. Fill in other details; submit
3. View results.

Actual results:

name cannot be used because "has already been taken"

Expected results:

I assume that the term "Internal" might probably be reserved or something, not sure. In any case, we should tell users they can't use that term, or provide some context indicating why exactly "Internal" can't be used.

Additional info: