Acquire tick lock in non-blocking mode, similarly to CMFActivity/ActivityTool.py: this allows a process_timer call to return quickly when previous tick is still processing. This prevents portal_alarms from using threads to just wait for one tic call to complete.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@23709 20353a03-c40f-0410-a6d1-a30d3c3de9de