it looks like the forest boundary is in the wrong place (it is overlapping the buildings). If you open the same location in JOSM, the forest boundary is in the right place. How can such a discrepancy exist? This is not a refresh issue - Mapnik has rendered the forest this way for months now.
Could be a problem in one of the imported diffs.
Cycpe Map, Transport Map and MapQuest Open do render the forest correctly, so I guess the server Mapnik is running on failed importing the current version of the area. This happens from time to time due to problems with the diffs, as far as I know. Either wait some time or try touching the area again to trigger an update/reimport.
I moved every problematic node, and on the next refresh, it was correctly updated. Thanks!