SF bug 563750 (Alex Martelli): posix_tmpfile():
The file returned by tmpfile() has mode w+b, so use that in the call
to PyFile_FromFile().
Bugfix candidate.
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index aafe7b1..c02d6a6 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -312,7 +312,7 @@
\end{funcdesc}
\begin{funcdesc}{tmpfile}{}
-Return a new file object opened in update mode (\samp{w+}). The file
+Return a new file object opened in update mode (\samp{w+b}). The file
has no directory entries associated with it and will be automatically
deleted once there are no file descriptors for the file.
Availability: \UNIX, Windows.