How to know where a reference name comes from?

Hi,

I faced a simple problem: on a repository, doing almost anything with
the reference "git-svn" complained about ambiguous reference. I know I
have a remotes/git-svn branch, but I didn't know what the other
reference could be.

I didn't find a command telling me _why_ this "git-svn" was ambiguous.
I'd have loved a

$ git rev-parse --all-symbolic-full-names git-svn

or so, but I couldn't find one.

Did I miss anything obvious? (not that the problem was big, I'm just
curious).

(I ended up doing "strace -e open git rev-parse git-svn", and found
out I had a .git/git-svn file lying around)

Thanks,

-- 
Matthieu