diff -r 7b0fd592cd08 Lib/test/test_warnings/__init__.py
--- a/Lib/test/test_warnings/__init__.py	Tue Apr 12 22:38:22 2016 +0200
+++ b/Lib/test/test_warnings/__init__.py	Wed Apr 13 02:48:35 2016 +0200
@@ -13,9 +13,17 @@ from test.test_warnings.data import stac
 
 import warnings as original_warnings
 
+# each "import warnings" calls _processoptions(sys.warnoptions) which can
+# change warning filters: save them to restore them after imports
+original_filters = original_warnings.filters.copy()
+
 py_warnings = support.import_fresh_module('warnings', blocked=['_warnings'])
 c_warnings = support.import_fresh_module('warnings', fresh=['_warnings'])
 
+original_warnings.filters[:] = original_filters
+del original_filters
+
+
 @contextmanager
 def warnings_state(module):
     """Use a specific warnings implementation in warning_tests."""