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:    Various code is not fully tested.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes vim/vim#8378)
https://github.com/vim/vim/commit/2d6d718dde7163c971d37b8f4f1ed8f2d25de130

Nvim does not support encoding=latin1 or compatible mode.
The two paste tests are applicable.

Problem:    Line number of option set by modeline is wrong.
Solution:   Do not double the line number. (Ozaki Kiichi, closes vim/vim#6035)
https://github.com/vim/vim/commit/5125874951669944a5f6a4163d6e5d437ae6321e

Problem:    Cannot disable modeline for an individual file.
Solution:   Recognize "nomodeline" in a modeline. (Hu Jialun, closes vim/vim#8798)
https://github.com/vim/vim/commit/9dcd349ca85e1df1abd1cbf1c29c0f1574b70bf8

Cherry-pick missing modeline for test_modeline.vim (heh) from v8.2.1432.

Problem:    Not all modeline variants are tested.
Solution:   Add modeline tests. (Dominique Pelle, closes vim/vim#5369)
https://github.com/vim/vim/commit/e74331db4b1b6a64fbbc188ff9bc472a478b9a4e

Problem:    Misspelled mkspellmem as makespellmem.
Solution:   Drop duplicate help entry, fix test. (Naruhiko Nishino, Ken
            Takata, closes vim/vim#4437)
https://github.com/vim/vim/commit/076073950c44ea0e35bc39d539dc7ab41bf9c7ec

Problem:    Modeline test fails with python but without pythonhome.
Solution:   Correct test argument.
https://github.com/vim/vim/commit/e09244ee3567d658c293fb1ae0d47a1a8be870ac

Problem:    can set 'modelineexpr' in modeline.
Solution:   Add P_SECURE flag.
https://github.com/vim/vim/commit/7e800c6047c8a9cc3e5cbc019a4dc91ec36616b1

Problem:    Using expressions in a modeline is unsafe.
Solution:   Disallow using expressions in a modeline, unless the
            'modelineexpr' option is set.  Update help, add more tests.
https://github.com/vim/vim/commit/110289e78195b6d01e1e6ad26ad450de476d41c1

Problem:    Modeline test with keymap still fails.
Solution:   Check that the keymap feature is available for the failure assert.
https://github.com/vim/vim/commit/3067a4dd0d768d1e4a47cf3c100f3e2b462717d7