Cant push branch or tag with German characters

If I try to push a repository with German characters like äöüß I get an

remote: /usr/local/lib/ruby/2.1.0/json/common.rb:223:in `encode': "\xC3" from ASCII-8BIT to UTF-8 (Encoding::UndefinedConversionError)
remote:         from /usr/local/lib/ruby/2.1.0/json/common.rb:223:in `generate'
remote:         from /usr/local/lib/ruby/2.1.0/json/common.rb:223:in `generate'
remote:         from /usr/local/lib/ruby/2.1.0/json/common.rb:394:in `dump'
remote:         from /export/home/git/gitlab-shell/lib/gitlab_update.rb:56:in `update_redis'
remote:         from /export/home/git/gitlab-shell/lib/gitlab_update.rb:40:in `exec'
remote:         from hooks/update:14:in `<main>'

This is I big issue for us, because in old projects we have such tags and branches.