Redmine

I get an 'invalid byte sequence in US-ASCII' error when updating from one of my git repositories. The problem is a commit message with '§$%&$' as part of the commit message. Any idea how to fix it?

ArgumentError (invalid byte sequence in US-ASCII):
  lib/redmine/scm/adapters/git_adapter.rb:133:in `block (2 levels) in revisions'
  lib/redmine/scm/adapters/git_adapter.rb:132:in `each_line'
  lib/redmine/scm/adapters/git_adapter.rb:132:in `block in revisions'
  lib/redmine/scm/adapters/abstract_adapter.rb:193:in `call'
  lib/redmine/scm/adapters/abstract_adapter.rb:193:in `block in shellout'
  lib/redmine/scm/adapters/abstract_adapter.rb:191:in `popen'
  lib/redmine/scm/adapters/abstract_adapter.rb:191:in `shellout'
  lib/redmine/scm/adapters/abstract_adapter.rb:177:in `shellout'
  lib/redmine/scm/adapters/git_adapter.rb:126:in `revisions'
  app/models/repository/git.rb:52:in `fetch_changesets'
  app/controllers/repositories_controller.rb:77:in `show'
  <internal:prelude>:8:in `synchronize'
  thin (1.2.7) lib/thin/connection.rb:76:in `block in pre_process'
  thin (1.2.7) lib/thin/connection.rb:74:in `catch'
  thin (1.2.7) lib/thin/connection.rb:74:in `pre_process'
  thin (1.2.7) lib/thin/connection.rb:57:in `process'
  thin (1.2.7) lib/thin/connection.rb:42:in `receive_data'
  eventmachine (0.12.10) lib/eventmachine.rb:256:in `run_machine'
  eventmachine (0.12.10) lib/eventmachine.rb:256:in `run'
  thin (1.2.7) lib/thin/backends/base.rb:57:in `start'
  thin (1.2.7) lib/thin/server.rb:156:in `start'
  thin (1.2.7) lib/thin/controllers/controller.rb:80:in `start'
  thin (1.2.7) lib/thin/runner.rb:177:in `run_command'
  thin (1.2.7) lib/thin/runner.rb:143:in `run!'
  thin (1.2.7) bin/thin:6:in `<top (required)>'
  /usr/local/bin/thin:19:in `load'
  /usr/local/bin/thin:19:in `<main>'