Make sure that CI_COMMIT_REF_PROTECTED is a bool

app/models/ci/pipeline.rb

@@ -638,7 +638,7 @@ module Ci
         variables.append(key: 'CI_COMMIT_MESSAGE', value: git_commit_message.to_s)
         variables.append(key: 'CI_COMMIT_TITLE', value: git_commit_full_title.to_s)
         variables.append(key: 'CI_COMMIT_DESCRIPTION', value: git_commit_description.to_s)
-        variables.append(key: 'CI_COMMIT_REF_PROTECTED', value: protected_ref?.to_s)
+        variables.append(key: 'CI_COMMIT_REF_PROTECTED', value: (!!protected_ref?).to_s)
 
         if merge_request_event? && merge_request
           variables.append(key: 'CI_MERGE_REQUEST_SOURCE_BRANCH_SHA', value: source_sha.to_s)

spec/models/ci/build_spec.rb

@@ -2228,7 +2228,7 @@ describe Ci::Build do
           { key: 'CI_COMMIT_MESSAGE', value: pipeline.git_commit_message, public: true, masked: false },
           { key: 'CI_COMMIT_TITLE', value: pipeline.git_commit_title, public: true, masked: false },
           { key: 'CI_COMMIT_DESCRIPTION', value: pipeline.git_commit_description, public: true, masked: false },
-          { key: 'CI_COMMIT_REF_PROTECTED', value: pipeline.protected_ref?.to_s, public: true, masked: false }
+          { key: 'CI_COMMIT_REF_PROTECTED', value: (!!pipeline.protected_ref?).to_s, public: true, masked: false }
         ]
       end