What is your use case, Poul-Henning?

It looks like the module has never set the file mode, at least since it was added to Python in 1994. I suggest just remove the dead code and fix the documentation. At least you shouldn’t make this change in bug fix releases. It is just as likely to break people’s code as fix it.

If you do want to change the behaviour, I suggest using “os.open” to set the mode when the file is created. Otherwise you risk errors and messing up the filesystem when using special files e.g. uu.decode(..., "/dev/null").