The new oldtest directory is in test/old/testdir. The reason for this is
that many tests have hardcoded the parent directory name to be
'testdir'.

Problem:    Not enough tests for buffer writing.
Solution:   Add more tests. Use CheckRunVimInTerminal in more places.
            (Yegappan Lakshmanan, closes vim/vim#6167)

https://github.com/vim/vim/commit/494e9069cb32620f7688a7cb128a3feff827639e

Problem:    Some terminals misinterpret the code for getting cursor style.
Solution:   Send a sequence to the terminal and check the result. (IWAMOTO
            Kouichi, closes vim/vim#2126)  Merged with current code.
https://github.com/vim/vim/commit/a45551a53557dba98973fdb3ff737dea2fffcda3

Cherry-pick Test_cwindow_highlight() from patch v8.1.2040
because it is skipped.

Problem:    Shared functions for testing are disorganised.
Solution:   Group finctions in script files. (Ozaki Kiichi, closes vim/vim#4573)
https://github.com/vim/vim/commit/7a39dd7f00239059ce34660611589b26126a550c

Problem:    Skipped tests are not properly listed.
Solution:   Throw a "Skipped" exception instead of using ":finish" or ":return".
https://github.com/vim/vim/commit/5d30ff19648d2ff0696cea97582b902f6a4ec0ba

Skips quite some (N/A) tests.

vim-patch:8.1.0503: missing change to diff test (included in cf1ffa916)

Problem:    Too many #ifdefs.
Solution:   Graduate FEAT_MBYTE, the final chapter.
https://github.com/vim/vim/commit/30276f2beb248557c6b33cd5418bca8b7084b0a5

Problem:    No test for 'ambiwidth' detection.
Solution:   Add a test.
https://github.com/vim/vim/commit/24839edc54e985ed88d063513226922a6f5b7554

https://github.com/vim/vim/commit/f71d7b9ee5ceba75f70c30845332ddd728fd16c6

Author: Bram Moolenaar <Bram@vim.org>
Date:   Tue Aug 9 22:14:05 2016 +0200

    patch 7.4.2189
    Problem:    Cannot detect encoding in a fifo.
    Solution:   Extend the stdin way of detecting encoding to fifo.  Add a test
                for detecting encoding on stdin and fifo. (Ken Takata)