Add missing file.

src/allmydata/test/common_py3.py

@@ -0,0 +1,42 @@
+"""
+Common utilities that have been ported to Python 3.
+
+Ported to Python 3.
+"""
+
+from __future__ import unicode_literals
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+from future.utils import PY2
+if PY2:
+    from builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, int, list, object, range, str, max, min  # noqa: F401
+
+import os
+import time
+
+
+class TimezoneMixin(object):
+
+    def setTimezone(self, timezone):
+        def tzset_if_possible():
+            # Windows doesn't have time.tzset().
+            if hasattr(time, 'tzset'):
+                time.tzset()
+
+        unset = object()
+        originalTimezone = os.environ.get('TZ', unset)
+        def restoreTimezone():
+            if originalTimezone is unset:
+                del os.environ['TZ']
+            else:
+                os.environ['TZ'] = originalTimezone
+            tzset_if_possible()
+
+        os.environ['TZ'] = timezone
+        self.addCleanup(restoreTimezone)
+        tzset_if_possible()
+
+    def have_working_tzset(self):
+        return hasattr(time, 'tzset')