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

Needed for later Vim patches.
Stub test_alot_latin.vim to avoid merge-conflict noise.

vim-patch:7.4.1700
vim-patch:7.4.1734
vim-patch:7.4.1740
vim-patch:7.4.2086
vim-patch:7.4.2223
vim-patch:8.0.0250

Problem:    Sourcing a script where a character has 0x80 as a second byte does
            not work. (Filipe L B Correia)
Solution:   Turn 0x80 into K_SPECIAL KS_SPECIAL KE_FILLER. (Christian
            Brabandt, closes vim/vim#728)  Add a test case.

https://github.com/vim/vim/commit/6bff02eb530aa29aafa2cb5627399837be7a5dd5

Problem:    Regexp test fails on windows.
Solution:   set 'isprint' to the right value for testing.

https://github.com/vim/vim/commit/490465bda6ab66f78041709cc02f48a25486a3e5

Problem:    The old regexp engine doesn't handle character classes correctly.
            (Manuel Ortega)
Solution:   Use regmbc() instead of regc().  Add a test.

https://github.com/vim/vim/commit/af98a49dd0ef1661b4998f118151fddbf6e4df75

Problem:    Using the system default encoding makes tests unpredictable.
Solution:   Always use utf-8 or latin1 in the new style tests.  Remove setting
            encoding and scriptencoding where it is not needed.

https://github.com/vim/vim/commit/ac105ed3c420660ddbddc501c97875c48220817e

Problem:    Using negative index in strcharpart(). (Yegappan Lakshmanan)
Solution:   Assume single byte when using a negative iindex.

https://github.com/vim/vim/commit/73dfe917ba6357413aaf98a021c91add5ac6e9bc

Problem:    Not testing utf-8 characters.
Solution:   Move the right asserts to the test_expr_utf8 test.

https://github.com/vim/vim/commit/b22bd46b9681d73d095f2eadff8163d3a6cf416b

Problem:    Test fails when not using utf-8.
Solution:   Split test in regularand utf-8 part.

https://github.com/vim/vim/commit/0f518a8f4d4be4cac10389680f6bd5e3781f94b0