Homebrew's python is now python3, but travis preinstalls old python2.
So updated Homebrew requires `brew upgrade python` now.

This commit disables auto update and use preinstalled version of Homebrew.

It depended on a global variable set by other tests.

* Prevent spurious message if taking a shortcut
* Fix YAML style
* Disable largefile tests

Separate tests leaked files or were depended on files leaked in other tests.

`writerows()` takes an iterable.

This is a simple grammatical fix correcting "...object whose `__self__` attributes is ..." to "...object whose `__self__` attribute is ...".

Fix typos in code comments: bdb.py and configure.ac.

The difference from before is that the settings are now on the
Highlights tab instead of the Extensions tab and only change one theme
at a time instead of all themes. The default for light themes is black
on light gray, as before. The default for the IDLE Dark theme is white
on dark gray, which better fits the dark theme.

When one starts IDLE from a console and loads a custom theme without
definitions for 'context', one will see a warning message on the console.
To stop the warning, go to Options => Configure IDLE => Highlights,
select the custom theme if not selected already, select 'Code Context',
and select foreground and background colors.

For bpo-32604 I added extra subinterpreter-related tests (see #6914), which caused a few buildbots to crash. This patch fixes the crash by ensuring that refcounts in channels are handled properly.

Instead of displaying a fixed number of lines, some blank, Code Context
now displays the variable number of actual context lines.  When there
are no context lines, it shows a single blank line to indicate that the
feature is turned on.

The Code Context configuration option is changed from 'numlines'
(default 3) to 'maxlines' (default 15) to avoid possible interference
between user settings for the old and new versions of Code Context.

Use also support.SOCK_MAX_SIZE, not only support.PIPE_MAX_SIZE, to
get the size for a blocking send into a multiprocessing pipe.

socketserver.ThreadingMixIn no longer tracks active threads if
block_on_close is false.

* "running:" progress: Format number of seconds as hours and minutes
* format_duration(): count also minutes as hours
* Create Lib/test/libregrtest/utils.py

Check which readline implementation is used based on the readline
docstring.

A check has been added in Logger.isEnabledFor() to return False when the logger is disabled. This avoids unnecessary work being done when a disabled logger is used.

* No longer clear filters, like --match, to re-run failed tests in
  verbose mode (-w option).
* Tests result: always indicate if tests have been interrupted.
* Enhance tests summary

Get the version of the C compiler.

For bpo-32604 I added some subinterpreter-related tests (see #6914) that are causing crashes on a few buildbots. I'm working on fixing the crashes (see #7251).  This change temporarily disables the triggering test.

Fix a crash in Python initialization when parsing the command line
options.

Fix memcpy() size parameter: previously, we read one wchar_t after
the end of _PyOS_optarg. Moreover, don't copy the trailingg NUL
character: we write it manually anyway.

Thanks Christoph Gohlke for the bug report and the fix!

85% of them are already links.

Fix test_ignore() of multiprocessing tests like
test_multiprocessing_forkserver: use support.PIPE_MAX_SIZE to make
sure that send_bytes() blocks.

* Add a space to ensurepip's --altinstall option
* Add periods to the arguments of ensurepip that didn't have it

This makes --help for all optional arguments consistent and also makes it
consistent with pip --help.