blocksize was hardcoded to 8192, preventing efficient upload when using
file-like body. Add blocksize argument to __init__, so users can
configure the blocksize to fit their needs.

I tested this uploading data from /dev/zero to a web server dropping the
received data, to test the overhead of the HTTPConnection.send() with a
file-like object.

Here is an example 10g upload with the default buffer size (8192):

$ time ~/src/cpython/release/python upload-httplib.py 10 https://localhost:8000/
Uploaded 10.00g in 17.53 seconds (584.00m/s)

real	0m17.574s
user	0m8.887s
sys	0m5.971s

Same with 512k blocksize:

$ time ~/src/cpython/release/python upload-httplib.py 10 https://localhost:8000/
Uploaded 10.00g in 6.60 seconds (1551.15m/s)

real	0m6.641s
user	0m3.426s
sys	0m2.162s

In real world usage the difference will be smaller, depending on the
local and remote storage and the network.

See https://github.com/nirs/http-bench for more info.

* Trivial cleanups following bpo-31370

* Also cleanup the "importlib._bootstrap_external" module

Replaces PROTOCOL_TLSv* and PROTOCOL_SSLv23 with PROTOCOL_TLS_CLIENT and
PROTOCOL_TLS_SERVER.
Signed-off-by: Christian Heimes <christian@python.org>

Includes patch by Ville Skyttä.

Original patch by Martin Panter, new policy fixes by me.

The previous attempt to determine the file’s Content-Length gave a false
positive for pipes on Windows.

Also, drop the special case for sending zero-length iterable bodies.

When the body object is a file, its size is no longer determined with
fstat(), since that can report the wrong result (e.g. reading from a pipe).
Instead, determine the size using seek(), or fall back to chunked encoding
for unseekable files.

Also, change the logic for detecting text files to check for TextIOBase
inheritance, rather than inspecting the “mode” attribute, which may not
exist (e.g. BytesIO and StringIO).  The Content-Length for text files is no
longer determined ahead of time, because the original logic could have been
wrong depending on the codec and newline translation settings.

Patch by Demian Brecht and Rolf Krahl, with a few tweaks by me.

The @reap_threads decorator made the test wait (for up to 1 s) until
background threads have finished.  Calling join() with a timeout should be
equivalent.

* No longer attempts to close already freed socket file descriptor
* Use socket object to be compatible with Windows
* Do not use a timeout to avoid complication with non-blocking mode
* Use internal localhost server rather than depending on a third party
* Avoid trouble with buffered HTTP data by testing tunnelled CONNECT data

Based on patch by Guido van Rossum.

Some http servers will reject PUT, POST, and PATCH requests if they
do not have a Content-Length header.

Patch by James Rutherford, with additional cleaning up of the
'request' documentation by me.

This changeset does two things: introduces a new RemoteDisconnected exception
(that subclasses ConnectionResetError and BadStatusLine) so that a remote
server disconnection can be detected by client code (and provides a better
error message for debugging purposes), and ensures that the client socket is
closed if a ConnectionError happens, so that the automatic re-connection code
can work if the application handles the error and continues on.

Tests are added that confirm that a connection is re-used or not re-used
as appropriate to the various combinations of protocol version and headers.

Patch by Martin Panter, reviewed by Demian Brecht.  (Tweaked only slightly by
me.)

Original patch by Demian Brecht.

with the constants in http.client.

Initial patch by Demian Brecht.

Also, document the LineTooLong exception since it can be raised by
the members of public API (e.g. http.client.HTTPResponse).

Patch by Martin Panter.

Patch by Demian Brecht.

Patch by Cory Benfield.

Added a new tunnel test to verify setting of _tunnel_host, _tunnel_port,
_tunnel_headers attributes on HTTPConnection object.

Patch by Demian Brecht.

value in the host header was set to "None".  Patch by Demian Brecht.

HTTPSConnection: prefer the context's check_hostname attribute over the constructor parameter (#22959)

Original patch by Martin Panter.

The svn.python.org server recently changed root certificate, causing the test
to fail. This backports revision 4985375db40f.

Patch by Alex Gaynor with some modifications by me.

Issue #7776: Fix ``Host:'' header and reconnection when using http.client.HTTPConnection.set_tunnel().

Patch by Nikolaus Rath.

Enhance HTTPResponse.readline() performance

Original patch by Simon Sapin.