What is the best way to make one of the branches of a subversion repository the new trunk?
There has been a major rewrite for the entire system: t
While the answers above will work, they aren't best practice. The latest svn server and client track merges for you. So svn knows which revisions you've merged into a branch and from where. This helps a lot when keeping a branch up-to-date and then merging it back into the trunk.
No matter which version of Subversion you're using however, there is a best practice method for getting changes in a branch back into trunk. It is outlined in the Subversion manual: Version Control with Subversion, Chapter 4. Branching and Merging, Keeping a Branch in Sync.