[Satellite 6] Content View import fails with 'no library repository found for Red_Hat_Enterprise_Linux_7_Server_-_Extras_RPMs_x86_64'

Issue

• We are importing a Content View (CV) from one Satellite server to another as part of the backup/migration/sync procedure:
  • Synchronizing Content Between Satellite Servers
• The import fails with a following error:

root@<hostname>:/var/lib/pulp/katello-export# ./import.sh
export-contentview1.tar
[.......................................................................................] [100%]
No new packages.
Could not import the content view:
Error: Unable to sync repositories, no library repository found for Red_Hat_Enterprise_Linux_7_Server_-_Extras_RPMs_x86_64