builds which got marked as "Keep this build forever" are deleted by "Discard old builds" even though the build.xml contains <keepLog>true</keepLog>.

however, there are additionally some rather old builds and build folders which start with "." still available on the hard disk but those aren't visible in the UI. This leads to that there are 380 builds on disk but the discard option is limited to 360.

Once a "kept" build is at position 360 then it will be removed after the next build.