Bug 1395717 - Use filename source-test tasks are defined in as part of their label, r=dustin

This creates a new "job-from" field that contains the relative filename the job was defined
in. The filename is relative to 'config.path'. If the task came from the 'jobs' key defined
in kind.yml, this field will be set to 'kind.yml'.

MozReview-Commit-ID: 9e1tEb6XuZT

taskcluster/taskgraph/loader/transform.py

@@ -5,7 +5,6 @@
 from __future__ import absolute_import, print_function, unicode_literals
 
 import logging
-import itertools
 
 from ..util.templates import merge
 from ..util.yaml import load_yaml
@@ -33,15 +32,19 @@ def loader(kind, path, config, params, loaded_tasks):
     """
     def jobs():
         defaults = config.get('job-defaults')
-        jobs = config.get('jobs', {}).iteritems()
-        jobs_from = itertools.chain.from_iterable(
-            load_yaml(path, filename).iteritems()
-            for filename in config.get('jobs-from', {}))
-        for name, job in itertools.chain(jobs, jobs_from):
+        for name, job in config.get('jobs', {}).iteritems():
             if defaults:
                 job = merge(defaults, job)
+            job['job-from'] = 'kind.yml'
             yield name, job
 
+        for filename in config.get('jobs-from', []):
+            for name, job in load_yaml(path, filename).iteritems():
+                if defaults:
+                    job = merge(defaults, job)
+                job['job-from'] = filename
+                yield name, job
+
     for name, job in jobs():
         job['name'] = name
         logger.debug("Generating tasks for {} {}".format(kind, name))