使用SVN合并跟踪时，防止工作副本过期

When using the merge tracking feature in Subversion 1.5, SVN updates the mergeinfo property of the parent folder to track the revisions being merged. We have a large number of developers (>500) working on our repository, and it is not uncommon around deadlines to have large numbers of developers all trying to commit around the same time. If some other developer has committed to the same folder since your last update, you are forced to update before committing due to the change in the mergeinfo. So how do you prevent the situation where a developer is forced to repeatedly update their working copy because each time they update, someone else commits to that folder before they do? Or is it rare enough of a situation that people just put up with it?When using the merge tracking feature in Subver