[Android] Lint pylib/base.

build/android/pylib/base/test_dispatcher.py

Index: build/android/pylib/base/test_dispatcher.py
diff --git a/build/android/pylib/base/test_dispatcher.py b/build/android/pylib/base/test_dispatcher.py
index 11374bbf45025bcf72d8e84ef3bf7b688dfdd7de..5f68a7ff46a648ea0685eb9ce53e5801dfa72fed 100644
--- a/build/android/pylib/base/test_dispatcher.py
+++ b/build/android/pylib/base/test_dispatcher.py
@@ -20,11 +20,10 @@ import threading
 
 from pylib import android_commands
 from pylib import constants
+from pylib.base import base_test_result
 from pylib.utils import reraiser_thread
 from pylib.utils import watchdog_timer
 
-import base_test_result
-
 
 DEFAULT_TIMEOUT = 7 * 60  # seven minutes
 
@@ -69,7 +68,9 @@ class _TestCollection(object):
     tests: List of tests to put in the collection.
   """
 
-  def __init__(self, tests=[]):
+  def __init__(self, tests=None):
+    if not tests:
+      tests = []
     self._lock = threading.Lock()
     self._tests = []
     self._tests_in_progress = 0