Logreader does not show logs even when logs are existent in logfile #67

The logreader does not show the configured loglevel logs, even if the logs are existent in the logfile.

Steps to reproduce

1. Enable "Debug" loglevel in logreader and let it fill the log for a while
2. Make sure to produce a few "Warning" logs
3. Disable again "Debug" Llglevel and set "Warning" as highest loglevel in logreader

Expected behaviour

Show only logs with a loglevel of "Warning" or higher

Actual behaviour

No logs show up at all, even though a manual look inside the logfile confirms that the logs exist.

Operating system: Docker Nextcloud
PHP version: 7.1.13
Nextcloud version: 12.0.5
Logread version: 2.0.0

I guess the logreader just checks the last X logs and shows them if necessary, but for a logread app I'm expecting it to check the whole log, not just the tip of the iceberg.