This hides unwanted implementation details from tracebacks.

And most of the tools.

Patch by Emanual Barry, reviewed by me, Serhiy Storchaka, and
Martin Panter.

This changes the main documentation, doc strings, source code comments, and a
couple error messages in the test suite. In some cases the word was removed
or edited some other way to fix the grammar.

Raise PendingDeprecationWarning when generator raises StopIteration
and no __future__ import is used.  Fix offenders in the stdlib
and tests.

See also issue 22906.
Thanks to Nick Coghlan and Berker Peksag for reviews.

Closes issue #22906.

Some applications (e.g. traditional Unix diff, version control
systems) neither know nor care about the encodings of the files they
are comparing. They are textual, but to the diff utility they are just
bytes. This worked fine under Python 2, because all of the hardcoded
strings in difflib.py are ASCII, so could safely be combined with
old-style u'' strings. But it stopped working in 3.x.

The solution is to use surrogate escapes for a lossless
bytes->str->bytes roundtrip. That means {unified,context}_diff() can
continue to just handle strings without worrying about bytes. Callers
who have to deal with bytes will need to change to using diff_bytes().

Use case: Mercurial's test runner uses difflib to compare current hg
output with known good output. But Mercurial's output is just bytes,
since it can contain:
  * file contents (arbitrary unknown encoding)
  * filenames (arbitrary unknown encoding)
  * usernames and commit messages (usually UTF-8, but not guaranteed
    because old versions of Mercurial did not enforce it)
  * user messages (locale encoding)

Since the output of any given hg command can include text in multiple
encodings, it is hopeless to try to treat it as decodable Unicode
text. It's just bytes, all the way down.

This is an elaboration of a patch by Terry Reedy.

Use two-argument form of next() and use a return-statement instead of an explicit raise StopIteration

Initial patch by Alba Magallanes.

requires them.  Disable executable bits and shebang lines in test and
benchmark files in order to prevent using a random system python, and in
source files of modules which don't provide command line interface.  Fixed
shebang line to use python3 executable in the unittestgui script.

Issue 10534, difflib: tweak doc; test new SequenceMatcher instance attributes; avoid unneeded lists of SM.b2j keys and items in .__chain_b. Do not backport.

Will add gone in 3.3 test later.

--no commit message

Issue 2986: Add autojunk paramater to SequenceMatcher to turn off heuristic. Patch by Terry Reedy, Eli Bendersky, and Simon Cross

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r80004 | r.david.murray | 2010-04-12 12:35:19 -0400 (Mon, 12 Apr 2010) | 13 lines

  Issue #7585: use tab between components in unified and context diff headers.

  Instead of spaces between the filename and date (or whatever the string
  is that follows the filename, if any) use tabs.  This is what the unix
  'diff' command does, for example, and difflib was intended to follow
  the 'standard' way of doing diffs.  This improves compatibility with
  patch tools.  The docs and examples are also changed to recommended that
  the date format used be the ISO 8601 format, which is what modern diff
  tools emit by default.

  Patch by Anatoly Techtonik.
........

Instead of spaces between the filename and date (or whatever the string
is that follows the filename, if any) use tabs.  This is what the unix
'diff' command does, for example, and difflib was intended to follow
the 'standard' way of doing diffs.  This improves compatibility with
patch tools.  The docs and examples are also changed to recommended that
the date format used be the ISO 8601 format, which is what modern diff
tools emit by default.

Patch by Anatoly Techtonik.

svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r76469 | senthil.kumaran | 2009-11-24 00:32:52 +0530 (Tue, 24 Nov 2009) | 10 lines

  Merged revisions 76464 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r76464 | senthil.kumaran | 2009-11-24 00:11:31 +0530 (Tue, 24 Nov 2009) | 4 lines

    Fix for issue1488943 - difflib.Differ() doesn't always add hints for tab
    characters.
  ........
................

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r76464 | senthil.kumaran | 2009-11-24 00:11:31 +0530 (Tue, 24 Nov 2009) | 4 lines

  Fix for issue1488943 - difflib.Differ() doesn't always add hints for tab
  characters.
........

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r76464 | senthil.kumaran | 2009-11-24 00:11:31 +0530 (Tue, 24 Nov 2009) | 4 lines

  Fix for issue1488943 - difflib.Differ() doesn't always add hints for tab
  characters.
........