class RuboCop::MagicComment::VimComment

# vim: foo=bar, fileencoding=ascii-8bit
# does nothing

# vim: foo=bar, fileencoding=ascii-8bit
# works

is at least one other token included in the string. For example
For some reason the fileencoding keyword only works if there

def encoding
  match('fileencoding') if tokens.size > 1
end