How to get rid of doubled branch after renaming a branch in svn-repository

[<pacco@tropezien.de>]

 Hi,

 I'm using git-svn as a tracking-tool for a Subversion repository.
 I currently detected an unexpected branch, seeming dead, but visible 
 using 'git branch -a'. I checked the svn log and saw that someone has 
 moved/renamed a branch. That results in a deletion of the old branch and 
 an adding of a copy of the old branch with the new branch name.

 The scenario is like that:

 $ git branch -a
 * master
   remotes/svnrepos/git-svn-test

 # Rename the branch (move) in the SVN-repos
 $ svn mv https://svn.repos/branches/git-svn-test 
 https://svn.repos/branches/git-svn-test-new

 # Update git-repository
 $ git svn fetch

 $ git branch -a
 * master
   remotes/svnrepos/git-svn-test
   remotes/svnrepos/git-svn-test-new

 You see the problem. Within Subversion simply a new repository version 
 now no longer "showing" the git-svn-test-branch was created. But within 
 git both branches stay visible.
 Well, I know that renaming a branch is really not that favoured action.
 But I expected that git-svn gathers also this deletion and removes the 
 obsolete branch.

 So, am I doing something wrong? Or am I expecting the wrong behaviour? 
 Or is that simply a feature, not a bug, and must be handled manually?