How to rollback a changeset in subversion

Suppose you want to rollback the changes in changeset 2340. You checkout the HEAD into some working directory, then do the following:
svn merge -c -2340 .
svn ci -m
Then you will probably want to set up the working copy so it has the changes you rolled back so you can fix whatever was wrong. Here's the command you use:
svn merge -c -2340 .
This is not very obvious to the beginner. It is done using merge rather than revert. The svn revert command is used to revert uncommitted changes.