(UnicodeEncodeError).

module name anymore, only work on unicode strings. Therefore it doesn't
truncate module names with embedded NUL characters, or fail if the module name
contains surrogate characters (UTF-8 encoder fails on a surrogate character).

Patch written by Alexander Belopolsky.

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.