Problem:    Not enough folding code is tested.
Solution:   Add more test cases. (Yegappan Lakshmanan, closes vim/vim#8046)

https://github.com/vim/vim/commit/5c504f680e63120fea36becfabb8d939d4449e34

Reorder test_fold.vim to match upstream.
Cherry-pick Test_fold_expr_error() from patch 8.2.0633.
Cherry-pick syntax feature check from patch 8.2.1432.
Cherry-pick a delete() call from patch 8.2.2112.

Problem:    Various errors not tested.
Solution:   Add tests. (Yegappan Lakshmanan, closes vim/vim#5895)

https://github.com/vim/vim/commit/476a613135bdc94e61c1dce8a9cbb4ab0b6dc2d1

Need to remove "F" flag from 'shortmess' as early as possible.

Problem:    Some code not covered by tests.
Solution:   Add test cases. (Yegappan Lakshmanan, closes vim/vim#5649)
https://github.com/vim/vim/commit/bc2b71d44a0b90b6aeb3534a76912fccbe5577df

Problem:    Insufficient code coverage for ex_docmd.c functions.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#5618)
https://github.com/vim/vim/commit/9f6277bdde97b7767ded43a0b5a2023eb601b3b7

Cherry-pick Test_window_only() from patch 8.2.0203.
Cherry-pick a memory leak fix from patch 8.2.0399.

Problem:    Stray ch_logfile() call.
Solution:   Remove it. (closes vim/vim#5503)
https://github.com/vim/vim/commit/ed5adff1e6da412732514d82363005f85fe22e04

Problem:    Script may be re-used when deleting and creating a new one.
Solution:   When the inode matches, also check the file name.
https://github.com/vim/vim/commit/ca33eb256eb910af05e8c9852bc9f716cece1f5c

Problem:    Tests do not run or are not reliable on some systems.
Solution:   Use "findstr" instead of "grep" on MS-Windows. Clear
            PROMPT_COMMAND in the terminal test. Delete temp file. Wait for
            output after executing a debug command. (Yegappan Lakshmanan,
            closes vim/vim#4479)
https://github.com/vim/vim/commit/ddd3308782e931a2c390d692cb23c40d8169bd6f

Ignored changes to testdir/test_terminal.vim.

Problem:    There is a SourcePre autocommand event but not a SourcePost.
Solution:   Add the SourcePost autocommand event. (closes vim/vim#3739)
https://github.com/vim/vim/commit/2b6185287adf53343ed5f49e967ae402c64063e4

Problem:    Source command doesn't check for the sandbox. (Armin Razmjou)
Solution:   Check for the sandbox when sourcing a file.
https://github.com/vim/vim/commit/53575521406739cf20bbe4e384d88e7dca11f040