Index: Lib/trace.py
===================================================================
--- Lib/trace.py	(revision 86193)
+++ Lib/trace.py	(working copy)
@@ -340,7 +340,7 @@
         """Return a coverage results file in path."""
 
         try:
-            outfile = open(path, "w")
+            outfile = open(path, "w", encoding="utf-8")
         except IOError as err:
             print(("trace: Could not open %r for writing: %s"
                                   "- skipping" % (path, err)), file=sys.stderr)