Bug 1420449: Skip schema validation with --fast r=dustin,ahal

MozReview-Commit-ID: 6wWYrNOG677

taskcluster/taskgraph/transforms/source_test.py

@@ -44,7 +44,7 @@ source_test_description_schema = Schema({
     # depend on a build task and the installer url will be saved to the
     # GECKO_INSTALLER_URL environment variable. Build labels are determined by the
     # `dependent-build-platforms` config in kind.yml.
-    Required('require-build', default=False): bool,
+    Required('require-build'): bool,
 
     # These fields can be keyed by "platform", and are otherwise identical to
     # job descriptions.
@@ -61,11 +61,19 @@ source_test_description_schema = Schema({
 transforms = TransformSequence()
 
 
+@transforms.add
+def set_defaults(config, jobs):
+    for job in jobs:
+        job.setdefault('require-build', False)
+        yield job
+
+
 @transforms.add
 def validate(config, jobs):
     for job in jobs:
-        yield validate_schema(source_test_description_schema, job,
-                              "In job {!r}:".format(job['name']))
+        validate_schema(source_test_description_schema, job,
+                        "In job {!r}:".format(job['name']))
+        yield job
 
 
 @transforms.add