Merge global defaults for jobs also

Currently, global defaults are merged to custom defaults for job
templates, but not for jobs.
Unify this behaviour.

Change-Id: I26fb2678df7f4225571bf7c3cd4be7041ce99217

jenkins_jobs/root_base.py

@@ -80,7 +80,7 @@ class RootBase:
             expanded_contents["description"] = amended_description
         return expanded_contents
 
-    def _pick_defaults(self, name, merge_global=True):
+    def _pick_defaults(self, name):
         try:
             defaults = self._defaults[name]
         except KeyError:
@@ -93,16 +93,13 @@ class RootBase:
             )
         if name == "global":
             return defaults
-        if merge_global:
+        return defaults.merged_with_global(self._pick_defaults("global"))
-            return defaults.merged_with_global(self._pick_defaults("global"))
-        else:
-            return defaults
 
 
 class NonTemplateRootMixin:
     def top_level_generate_items(self):
         try:
-            defaults = self._pick_defaults(self.defaults_name, merge_global=False)
+            defaults = self._pick_defaults(self.defaults_name)
             item_params = LocDict.merge(
                 defaults.params,
                 self.params,

tests/yamlparser/job_fixtures/concat_defaults003_job.xml

@@ -5,7 +5,7 @@
   <keepDependencies>false</keepDependencies>
   <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
   <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
-  <concurrentBuild>false</concurrentBuild>
+  <concurrentBuild>true</concurrentBuild>
   <canRoam>true</canRoam>
   <properties/>
   <scm class="hudson.scm.NullSCM"/>
@@ -15,5 +15,7 @@
     </hudson.tasks.Shell>
   </builders>
   <publishers/>
-  <buildWrappers/>
+  <buildWrappers>
+    <hudson.plugins.timestamper.TimestamperBuildWrapper/>
+  </buildWrappers>
 </project>

tests/yamlparser/job_fixtures/concat_defaults003_job.yaml

@@ -1,4 +1,5 @@
-# Global defaults are not used, not merged to custom ones if used from a job.
+# Global defaults are merged to custom ones if used from jobs,
+# not just from job templates.
 
 - defaults:
     name: global