This protects from possibilty of gc running just after fork.

Patch by Charles-François Natali

Fix suggested by Itay Brandes

Patch by Victor Stinner.

Patch by Victor Stinner.

Previously, if you passed in a bytes object, it would create a whole
new object.

There's no bufsize argument anymore, and os.fdopen() is only a very
thin wrapper around open() anymore. Change the documentation to
reflect that.

There is a rare edge case where the filesystem used by the tempfile functions
(usually /tmp) doesn't support xattrs while the one used by TESTFN (the current
directory, so likely to be below /home) does. This causes the xattr related
test_shutil tests fail. skip_unless_xattr now checks both.

I have also added skip_unless_xattr to __all__ where it has been missing.

Patch by Matej Cepl.

Patch by Matej Cepl.

Reverts some changes of d13fdd97cc8e.