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Description of problem:

On occasion, '-f -n 0' will show older log entries. Sometimes immediately, other times a few seconds after starting to follow the output.


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

[root@striker-m3 ~]# rpm -q systemd
systemd-219-30.el7_3.9.x86_64


How reproducible:

~75%


Steps to Reproduce:
1. Use logger to push a bunch of entries with a tag
2. Use 'journalctl -f -n 0 -t some-tag'
3. Old entries will sometimes be displayed

Actual results:

====
[root@striker-m3 ~]# date 
Tue Jun 13 07:09:05 CDT 2017

[root@striker-m3 ~]# journalctl -f -n 0 -t an-tools
-- Logs begin at Tue 2017-06-13 06:08:10 CDT. --
====

A few seconds later:

====
Jun 13 06:46:19 striker-m3.alteeve.com an-tools[21981]: Template.pm:191; <snip multi-line log entry>
====

Note that the old entries are sometimes single and other times multi-line log entries.


Expected results:

I understand that '-n 0' should show no older entries. Using 'journalctl -f -a -S "$(date +"%F %R:%S")" -t some-tag' produces the desired results (only show new entries), but this is obviously more cumbersome to type...


Additional info:

After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.