Remove duplication between bridge and job only policies

ee/lib/ee/gitlab/ci/config/entry/bridge.rb

@@ -15,15 +15,6 @@ module EE
 
             ALLOWED_KEYS = %i[trigger stage allow_failure only except].freeze
 
-            # TODO we probably need a common ancestor for a status / job
-            #
-            DEFAULT_ONLY_POLICY = {
-              refs: %w(branches tags)
-            }.freeze
-
-            DEFAULT_EXCEPT_POLICY = {
-            }.freeze
-
             validations do
               validates :config, allowed_keys: ALLOWED_KEYS
               validates :config, presence: true
@@ -39,7 +30,8 @@ module EE
               description: 'Pipeline stage this job will be executed into.'
 
             entry :only, ::Gitlab::Ci::Config::Entry::Policy,
-              description: 'Refs policy this job will be executed for.'
+              description: 'Refs policy this job will be executed for.',
+              default: ::Gitlab::Ci::Config::Entry::Policy::DEFAULT_ONLY
 
             entry :except, ::Gitlab::Ci::Config::Entry::Policy,
               description: 'Refs policy this job will be executed for.'
@@ -56,8 +48,8 @@ module EE
                 trigger: trigger_value,
                 ignore: !!allow_failure,
                 stage: stage_value,
-                only: DEFAULT_ONLY_POLICY.deep_merge(only_value.to_h),
-                except: DEFAULT_EXCEPT_POLICY.deep_merge(except_value.to_h) }
+                only: only_value,
+                except: except_value }.compact
             end
           end
         end

ee/spec/lib/gitlab/ci/config/entry/jobs_spec.rb

@@ -63,7 +63,6 @@ describe Gitlab::Ci::Config::Entry::Jobs do
             trigger: { project: 'my/project' },
             stage: 'test',
             only: { refs: %w[branches tags] },
-            except: {},
             ignore: false
           },
           regular_job: {
@@ -71,7 +70,6 @@ describe Gitlab::Ci::Config::Entry::Jobs do
             name: :regular_job,
             stage: 'test',
             only: { refs: %w[branches tags] },
-            except: {},
             ignore: false
           })
       end

lib/gitlab/ci/config/entry/job.rb

@@ -67,7 +67,7 @@ module Gitlab
 
           entry :only, Entry::Policy,
             description: 'Refs policy this job will be executed for.',
-            default: { refs: %w[branches tags] }
+            default: Entry::Policy::DEFAULT_ONLY
 
           entry :except, Entry::Policy,
             description: 'Refs policy this job will be executed for.'

lib/gitlab/ci/config/entry/policy.rb

@@ -11,6 +11,8 @@ module Gitlab
           strategy :RefsPolicy, if: -> (config) { config.is_a?(Array) }
           strategy :ComplexPolicy, if: -> (config) { config.is_a?(Hash) }
 
+          DEFAULT_ONLY = { refs: %w[branches tags] }.freeze
+
           class RefsPolicy < ::Gitlab::Config::Entry::Node
             include ::Gitlab::Config::Entry::Validatable