Description of problem:
After synchronizing Kickstart content, Installation Media is not available in the Location.

Version-Release number of selected component (if applicable):
pulp-server-2.8.3.4

How reproducible:
Not much.
I installed three Satellite 6.2 with two install media each (6.8 + 7.2):
* first didnt' show any install media
* second had both install media available
* third was missing the 7.2 install media, 6.8 was available

Steps to Reproduce:
1. install Satellite, add manifest
2. in Red Hat Repositories => Kickstarts, select RHEL 6.8 + 7.2
3. in Content => Sync Status, sync both kickstarts
4. in Administer => Locations, check that both Installation Media can be affected to the Location

Actual results:
Sometimes some Installation Media are missing

Expected results:
All Installation Media always available to select in the Location

Additional info:
The solution I found is to:
* Disable the relevant Kickstart in Content => Red Hat Repositories => Kickstarts.
* Run "foreman-rake katello:delete_orphaned_content RAILS_ENV=production"
* Run "tail -f /var/log/messages | grep pulp"
* Wait for a message like "Task pulp.server.managers.content.orphan.delete_all_orphans[ID] succeeded" to appear
* Re-enable the Kickstart in Content => Red Hat Repositories => Kickstarts
* Download its content again in Content => Sync Status.