'git svn' does not start git-svn any more

On my linux system (Centos 5.9) ‘git svn‘ stopped working and I don’t know why and how.

output is:

$ git svn
git: 'svn' is not a git command. See 'git --help'.

/usr/libexec/git-core/git-svn exists and is fully working ( I can start it manually). And all other git sub commands seem to work (at least the ones I tried).

I’m not aware of any action which can have impact on git-svn like this (e.g. no updates/restarts)

How does git ‘find’ the git-svn script? Is there a mapping which might be broken or does git look into /usr/libexec/git-core?

What has happened?

Git Baby is a git and github fan, let's start git clone.