Are you getting “The specified baseline is not the latest baseline, so it may not be checked out. Checkout of ‘/svn/yourrepo/!svn/bln/123456’: 409 Conflict (https://svnserver.com)” when trying to commit to Subversion? I’ve setup a Subversion write-through proxy to improve multi-site performance. Unfortunately this seems to be one of the downsides.
The solution to the above is to update and try committing again. It is possible you may need to wait until your write-through proxy has synced with the master before it will work.