Description of problem:

Unable to change base channel from RHEL-7.2 EUS --> RHEL-7.3 EUS and vice versa.

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

v.5.7

How reproducible:

Only at customer's environment

Steps to Reproduce:

1. Ensure rhel7.2 EUS and rhel 7.3 EUS channels are synced.
2. Register a rhel7 system to the satellite. 
3. Try to change base channel of the system from RHEL-7.2 EUS --> RHEL-7.3 EUS and vice versa

Actual results:

- Can not change base channel from RHEL-7.2 EUS --> RHEL-7.3 EUS and vice versa.

- We need to first change the base channel from :

RHEL7.2 EUS --> RHEL-7 (base channel) --> RHEL-7.3 EUS

RHEL7.3 EUS --> RHEL-7 (base channel) --> RHEL-7.2 EUS

Expected results:

We should be able to change the base channel from RHEL 7.2 EUS to RHEL 7.3 EUS directly, with out needing to change the same to RHEL-7base channel

Additional info:

The part of the above issue is also related to a Bug which I have separately opened [https://bugzilla.redhat.com/show_bug.cgi?id=1442312]