Ensure that secrets masking does not change bytesize

lib/gitlab/ci/mask_secret.rb

@@ -9,11 +9,7 @@ module Gitlab
         # We assume 'value' must be mutable, given
         # that frozen string is enabled.
 
-        ##
-        # TODO We need to remove this because it is going to change checksum of
-        # a trace.
-        #
-        value.gsub!(token, 'x' * token.length)
+        value.gsub!(token, 'x' * token.bytesize)
         value
       end
     end

spec/lib/gitlab/ci/mask_secret_spec.rb

@@ -22,6 +22,10 @@ RSpec.describe Gitlab::Ci::MaskSecret do
       expect(mask('token', nil)).to eq('token')
     end
 
+    it 'does not change a bytesize of a value' do
+      expect(mask('token-ü/unicode', 'token-ü').bytesize).to eq 16
+    end
+
     def mask(value, token)
       subject.mask!(value.dup, token)
     end