git branch --track and remote branches with / in the name

Hi, the --track option to git branch or git checkout doesn't work for
remote branches that contain a slash in the name:

 $ tail -n6 .git/config
 [remote "origin"]
         url = /tmp/repo
         fetch = +refs/heads/*:refs/remotes/origin/*
 [branch "master"]
         remote = origin
         merge = refs/heads/master
 $ git branch -r
   origin/HEAD
   origin/b
   origin/foo/b
   origin/master
 $ git branch --track b origin/b    
 Branch b set up to track remote branch refs/remotes/origin/b.
 $ git branch --track foo/b origin/foo/b
 $ tail -n6 .git/config
 [branch "master"]
         remote = origin
         merge = refs/heads/master
 [branch "b"]
         remote = origin
         merge = refs/heads/b
 $ 

Regards, Gerrit.