Don't issue try jobs for OWNERS-only changes.

PRESUBMIT_test.py

Index: PRESUBMIT_test.py
diff --git a/PRESUBMIT_test.py b/PRESUBMIT_test.py
index 979ad892f1a58278ef1f248fd462ffc67b7824ee..6a29aca96ed4af7dbb7c506f920e8d6b0b000b7a 100755
--- a/PRESUBMIT_test.py
+++ b/PRESUBMIT_test.py
@@ -60,6 +60,14 @@ class MockFile(object):
     return self._local_path
 
 
+class MockChange(object):
+  def __init__(self, changed_files):
+    self._changed_files = changed_files
+
+  def LocalPaths(self):
+    return self._changed_files
+
+
 class IncludeOrderTest(unittest.TestCase):
   def testSystemHeaderOrder(self):
     scope = [(1, '#include <csystem.h>'),
@@ -339,6 +347,14 @@ class BadExtensionsTest(unittest.TestCase):
     results = PRESUBMIT._CheckPatchFiles(mock_input_api, MockOutputApi())
     self.assertEqual(0, len(results))
 
+  def testOnlyOwnersFiles(self):
+    mock_change = MockChange([
+      'some/path/OWNERS',
+      'A\Windows\Path\OWNERS',
+    ])
+    results = PRESUBMIT.GetPreferredTrySlaves(None, mock_change)
+    self.assertEqual(0, len(results))
+
 
 if __name__ == '__main__':
   unittest.main()