An svn repository I\'m mirroring through git-svn has changed URL.
In vanilla svn you\'d just do svn switch --relocate old_url_base new_url_base.
Git svn relies heavily on the svn URL. Every commit that is imported from svn has a git-svn-id that includes the svn URL.
A valid relocations strategy is to call git-svn clone on the new repository and merge the changes onto that new close. For a more detailed procedure, see this article:
http://www.sanityinc.com/articles/relocating-git-svn-repositories