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:    Crash when using buffer-local user command in cmdline window.
            (Karl Yngve Lervåg)
Solution:   Use the right buffer to find the user command. (closes vim/vim#12030,
            closes vim/vim#12029)

https://github.com/vim/vim/commit/b444ee761a2956a996a75d923281c51fa1a759f3

Problem:    Expand functions use confusing argument names.
Solution:   Rename "file" to "match".  Refactor some completion code.  Add a
            few more tests. (Yegappan Lakshmanan, closes vim/vim#9790)

https://github.com/vim/vim/commit/24384308635f40b15d399fbd4e60c25d5e21ed8d

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

Problem:    Leaking memory when defining a user command fails.
Solution:   Free "compl_arg" when needed. (closes vim/vim#11726)

https://github.com/vim/vim/commit/33e543038b84af7557ab9ecff500fc4ab98dd2a3

Problem:    Not enough tests for command line completion.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes vim/vim#9771)

https://github.com/vim/vim/commit/9773db6f9bce7a6f063e23179976d7825ace4d72

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

Problem:    Not enough tests for command line completion.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes vim/vim#9760)

https://github.com/vim/vim/commit/4d03d870007c593bce2cfa8d0a6597ca3a20fa35

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

Problem:    Null dict is not handled like an empty dict.
Solution:   Fix the code and add tests. (Yegappan Lakshmanan, closes vim/vim#5968)

https://github.com/vim/vim/commit/ea04a6e8baff2f27da7cdd54bf70a5525994f76d

Nvim doesn't support modifying NULL list, so comment out a line.

Problem:    Code in eval.c not sufficiently covered by tests.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#5815)

https://github.com/vim/vim/commit/8b633135106dda8605463b780573c45b00c22afe

Nvim does not have v:none, so comment out test for it.

Problem:    User command does not get number from :tab modifier.
Solution:   Include the number. (closes vim/vim#11393, closes vim/vim#6901)
https://github.com/vim/vim/commit/208567e9d744ef7b89bed1f62e951ae4ee2f6f5f

Problem:    :horizontal modifier not fully supported.
Solution:   Also use :horizontal for completion and user commands.
            (closes vim/vim#11025)
https://github.com/vim/vim/commit/d3de178e5352fedf0f30b979f46a2fcbca24ea40