Bug 1402457 - fix the file update target task to not schedule the wor…

…ld. r=aki

for: Run buildbot's periodic_file_update job scheduled via taskcluster.

I messed up thinking this was filter-out not filter in the target task method.
I'm also renaming the target_task method in order to avoid these decision jobs
from needing to contact balrog for partial data (because it had 'nightly' in the
target task name.

MozReview-Commit-ID: 3uetnWG4vnW

.cron.yml

@@ -102,7 +102,13 @@ jobs:
       job:
           type: decision-task
           treeherder-symbol: Nfile
-          target-tasks-method: nightly_file_update
+          target-tasks-method: file_update
       run-on-projects:
           - mozilla-central
-      when: []  # don't run for now due to unforeseen issues
+      when:
+          by-project:
+              # No default branch
+              mozilla-central:
+                  # Buildbot start time is 10:02am UTC, until we are able to
+                  # disable buildbot scheduling, use +12h
+                  - {hour: 22, minute: 0}

taskcluster/taskgraph/target_tasks.py

@@ -390,11 +390,11 @@ def filter(task):
     return [l for l, t in full_task_graph.tasks.iteritems() if filter(t)]
 
 
-@_target_task('nightly_file_update')
+@_target_task('file_update')
 def target_tasks_file_update(full_task_graph, parameters):
     """Select the set of tasks required to perform nightly in-tree file updates
     """
     def filter(task):
         # For now any task in the repo-update kind is ok
-        return task.kind not in ['repo-update']
+        return task.kind in ['repo-update']
     return [l for l, t in full_task_graph.tasks.iteritems() if filter(t)]