Enforce quoting style in Travis. (#4589)

python/ray/tests/test_autoscaler.py

@@ -388,7 +388,7 @@ class AutoscalingTest(unittest.TestCase):
         rtc1.clear()
         autoscaler.update()
         # Synchronization: wait for launchy thread to be blocked on rtc1
-        if hasattr(rtc1, '_cond'):  # Python 3.5
+        if hasattr(rtc1, "_cond"):  # Python 3.5
             waiters = rtc1._cond._waiters
         else:  # Python 2.7
             waiters = rtc1._Event__cond._Condition__waiters
@@ -539,9 +539,9 @@ class AutoscalingTest(unittest.TestCase):
 
     def testReportsConfigFailures(self):
         config = copy.deepcopy(SMALL_CLUSTER)
-        config['provider']['type'] = 'external'
+        config["provider"]["type"] = "external"
         config = fillout_defaults(config)
-        config['provider']['type'] = 'mock'
+        config["provider"]["type"] = "mock"
         config_path = self.write_config(config)
         self.provider = MockProvider()
         runner = MockProcessRunner(fail_cmds=["cmd1"])