Do not require Ci config node to have a hash value

lib/gitlab/ci/config/node/configurable.rb

@@ -5,6 +5,14 @@ module Gitlab
         module Configurable
           extend ActiveSupport::Concern
 
+          def initialize(*)
+            super
+
+            unless leaf? || has_config?
+              @errors << 'should be a configuration entry with hash value'
+            end
+          end
+
           def keys
             self.class.nodes || {}
           end

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

@@ -13,10 +13,6 @@ module Gitlab
             @parent = parent
             @nodes = {}
             @errors = []
-
-            unless leaf? || has_config?
-              @errors << 'should be a configuration entry with hash value'
-            end
           end
 
           def process!