Extract common `when` code between CI/CD processables

app/models/ci/bridge.rb

@@ -37,13 +37,6 @@ module Ci
       false
     end
 
-    ##
-    # TODO we probably want to add support for `when` configuration.
-    #
-    def when
-      'on_success'
-    end
-
     def expanded_environment_name
     end
 

app/models/ci/build.rb

@@ -639,10 +639,6 @@ module Ci
       super || project.try(:build_coverage_regex)
     end
 
-    def when
-      read_attribute(:when) || 'on_success'
-    end
-
     def options
       read_metadata_attribute(:options, :config_options, {})
     end

app/models/concerns/ci/processable.rb

@@ -17,7 +17,7 @@ module Ci
     end
 
     def when
-      raise NotImplementedError
+      read_attribute(:when) || 'on_success'
     end
 
     def expanded_environment_name