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:    Several errors are not tested for.
Solution:   Add tests. (Yegappan Lakshmanan, closes vim/vim#5892)
https://github.com/vim/vim/commit/ee4e0c1e9a81cb5d96e0060203a9033c2f28588e

Omit Test_range() change: reverted in patch 8.2.0615.
Cherry-pick Test_z_no_space_before_xxx() from patch 8.2.0195.
Cherry-pick Test_reverse_sort_uniq() change from patch 8.2.0183.
Make uniq() error behavior consistent with sort().
Cherry-pick Test_set_ttytype() change from patch 8.1.1826.
Cherry-pick quickfix checks from patch 8.1.2373 to test_preview.vim.
Test_viminfo_error() is applicable.
Cherry-pick E1058 from patch 8.2.0149 and port Test_deep_nest() to Lua.

Problem:    Various code not covered by tests.
Solution:   Add more test coverage. (Yegappan Lakshmanan, closes vim/vim#5720)
https://github.com/vim/vim/commit/91ffc8a5f5c7b1c6979b3352a12ed779d11173a9

Test_Ex_echo_backslash() is not applicable to Vim enhanced Ex mode.

Problem:    Digraph test fails when LC_ALL is set to "C".
Solution:   When restoring 'encoding' set it to "utf-8". (closes vim/vim#8742)
https://github.com/vim/vim/commit/52eb372a04dfc5d5afef238c1b3c4a8e92020837

Problem:    New digraph functions use old naming scheme.
Solution:   Use the digraph_ prefix. (Hirohito Higashi, closes vim/vim#8580)
https://github.com/vim/vim/commit/29b857150c111a455f1a38a8f748243524f692e1

Problem:    Cannot add a digraph with a leading space.  It is not easy to list
            existing digraphs.
Solution:   Add setdigraph(), setdigraphlist(), getdigraph() and
            getdigraphlist(). (closes vim/vim#8580)
https://github.com/vim/vim/commit/6106504e9edc8500131f7a36e59bc146f90180fa

Use GA_APPEND_VIA_PTR in registerdigraph().
Use tv_list_append_*() in getdigraphlist_appendpair().
Put the error messages in digraph.c.
E196 is N/A.
Remove mentions about 'encoding' being non-Unicode.
Nvim doesn't support setting encoding=japan, so skip a test.

Problem:    Various typos in source files and tests.
Solution:   Fix the typos. (Emir Sari, closes vim/vim#5532)
https://github.com/vim/vim/commit/4b96df5a017a04141c4e901b1fc5704a3ca48099

Problem:    Some errors are not covered by tests.
Solution:   Add a few more tests. (Dominique Pelle, closes vim/vim#5920)
https://github.com/vim/vim/commit/067297e16a516838dbc46aaa9d8b1a507afec28d

Problem:    Tabpage menu and tabline not sufficiently tested.
Solution:   Add tests. (Yegappan Lakshmanan, closes vim/vim#6307)
https://github.com/vim/vim/commit/8c524f76ebd43f006e765534765b595de7095f12

Cherry-pick Test_entering_digraph() from patch v8.2.1022.
Cherry-pick :CheckGui from patch v8.1.1826.

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