encoding using _Py_char2wchar() instead of mbstowcs() to store undecodable
bytes as surrogates characters (PEP 383) instead of ignoring silently
the PYTHONPATH variable.

This prevents the assignment of __class__ in the class body from breaking
super. (Although a determined person could do locals()["@__class__"] = 4)

Original patch by Vinay Sajip on #11637.

Andrew agreed in the issue that eliminating the module file made sense.
Wrapper has only been exposed as a function, and so there is no (easy)
way to access the wrapper module, which in any case only had the one
function in it.  Since __init__ already contains a couple wrapper
functions, it seems to make sense to just move wrapper there instead of
importing it from a single function module.

Patch by July Tikhonov.

Analogous to the decode_header fix, this fix makes Header.append and
make_header correctly handle the unknown-8bit charset introduced by email5.1,
when the input to them is binary strings.  Previous to this fix the
make_header(decode_header(x)) == x invariant was broken in the face of the
unknown-8bit charset.

This updates 12e39cd7a0e4 (merge of b21fdfa0019c), which fixed this bug
incorrectly.

This updates b21fdfa0019c, which fixed this bug incorrectly.

This makes them work like the close provided by regular file objects.