From fcc2a21fae20b312e913a26121a12752ba768ad1 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@haypocalc.com>
Date: Wed, 29 Jun 2011 20:01:29 +0200
Subject: [PATCH] Issue #12400: regrtest.runtest() uses stream.seek(0) before
 .truncate()

.truncate(0) doesn't rewind.
---
 Lib/test/regrtest.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index f1ef7156103..14fa00591b9 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -791,9 +791,12 @@ def runtest(test, verbose, quiet,
             # tests keep a reference to sys.stdout or sys.stderr
             # (eg. test_argparse).
             if runtest.stringio is None:
-                runtest.stringio = io.StringIO()
-            stream = runtest.stringio
-            stream.truncate(0)
+                stream = io.StringIO()
+                runtest.stringio = stream
+            else:
+                stream = runtest.stringio
+                stream.seek(0)
+                stream.truncate()
 
             orig_stdout = sys.stdout
             orig_stderr = sys.stderr