I hit my head about it for a while, but found out the reason
If you have a secure svn repository you should use
$ svn2git http://svn.example.com/path/to/repo --username <<user_with_perms>>
but it does not ask for a password unless you press "Enter". (and of course he does not give you any instructions)
In my case, we had a non-standard structured repo, so I used;
$ svn2git http://svn.example.com/path/to/repo --username <<user_with_perms>> --rootistrunk -v
- verbose or -v really helps btw
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