Continuing from https://bugzilla.redhat.com/show_bug.cgi?id=1404406#c9
Description of problem:
When journalctl encounters a journal file which it is unable to open due to an incomatiblity flag being set in the journal file header, journalctl exits with a generic message "<...> uses an unsupported feature." without any specific information which feature requires support that isn't available or wasn't compiled in.
For example, #1404406, had a regression in which lz4 support wasn't compiled into the shipped package and journal files could no longer be opened by journalctl.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. compiled systemd without support for the compression algo used to compress the journal files
2. try to open a compressed journal file.
journalctl reports " "<...> uses an unsupported feature."
should say " "<...> requires support for XXX, which is not available."
This bug appears to have been reported against 'rawhide' during the Fedora 26 development cycle.
Changing version to '26'.