Index: tarfile.py
===================================================================
--- tarfile.py	(revision 52498)
+++ tarfile.py	(working copy)
@@ -1618,6 +1618,8 @@
         """
         source = self.extractfile(tarinfo)
         target = file(targetpath, "wb")
+        if sys.platform == "win32":
+            target.truncate(tarinfo.size)
         copyfileobj(source, target)
         source.close()
         target.close()