added additional test case

spec/models/ci/build_spec.rb

@@ -974,6 +974,7 @@ describe Ci::Build, :models do
       'a' * 64                => 'a' * 63,
       'FOO'                   => 'foo',
       '-' + 'a' * 61 + '-'    => 'a' * 61,
+      '-' + 'a' * 63 + '-'    => 'a' * 63,
       'a' * 62 + ' '          => 'a' * 62
     }.each do |ref, slug|
       it "transforms #{ref} to #{slug}" do