Description of problem:

Every rhn_check call on client creates new 'Updated system release' record in System History on the server

https://satellite/rhn/systems/details/history/History.do?sid=1000100684&

Type 	Status 	Summary 	Time
 (n/a) 	Updated system release from 24 to 24 	Tue Nov 22 04:18:17 EST 2016
(n/a) 	Updated system release from 24 to 24 	Tue Nov 22 04:17:36 EST 2016 


Version-Release number of selected component (if applicable):
rhn-check-2.5.16-1.fc24
rhn-check-2.7.1-1.fc24

How reproducible:
always

Steps to Reproduce:
1. register Fedora client to Spacewalk or Satellite
2. rhn_check
3. see https://satellite/rhn/systems/details/history/History.do?sid=sistem_id

Actual results:
rhn_check creates new Updated system release from 24 to 24 records in System History

Expected results:
at most one update system release message when release version is really changed

Additional info:
could not reproduce on RHEL