Problem:    Some tests fail when run as root.
Solution:   Add CheckNotRoot and use it. (James McCoy, closes vim/vim#5020)
https://github.com/vim/vim/commit/07282f01da06c158bab4787adc89ec15d7eeb202

Skip test_terminal.vim and test_viminfo.vim: N/A

Prep for patch v8.2.0511.

Problem:    Various comments can be improved.
Solution:   Various comment adjustments.
https://github.com/vim/vim/commit/22286895fce0e45e42126c7f2e35ebf43bc625d9

Problem:    Screenshot tests may use a different encoding. (Dominique Pelle)
Solution:   Always set 'encoding' to "utf-8" when running Vim in a terminal.
            (closes vim/vim#4884)
https://github.com/vim/vim/commit/0fdddeeb66bbe326860ddfc573eba42f6487bbda

Comment out the encoding change in shared.vim
because Neovim always uses utf-8 for internal character encoding.

Problem:    Netbeans test sometimes fails.
Solution:   Mark any test using an external command as flaky.
https://github.com/vim/vim/commit/4a070cc82e00618db279526797564cb2b4e9b060

Problem:    When testing in the GUI may try to run gvim in a terminal.
Solution:   Add the -v argument. (Yee Cheng Chin, closes vim/vim#4605)  Don't skip
            tests that work now.
https://github.com/vim/vim/commit/0d702028feb859e6bde9a0c943d398d86294beb7

vim-patch:8.2.1754: completion with spell checking not tested

Problem:    Completion with spell checking not tested.
Solution:   Add a test case. (Dominique Pellé, closes vim/vim#7024)
https://github.com/vim/vim/commit/8c7ad3631af570f68b2da2658cf966a9a19cb6c4

Cherry-pick GetMessages() from patch 8.2.0666.
Comment out the code that checks for "Messages maintainer:" line
because Neovim's ":messages" command does not output it
and patches for the "methods" feature (ie. foo->bar) are not ported yet.

https://github.com/neovim/neovim/pull/5160

Problem:    The RUN_VIM variable is longer than needed.
Solution:   Shorten RUN_VIM. (Daniel Hahler, closes vim/vim#4643)
https://github.com/vim/vim/commit/41a82604453080d0011f281532582d3bd360df4a

Problem:    Confusing skipped message.
Solution:   Drop "run" from "run start the GUI".
https://github.com/vim/vim/commit/2514315fc2530170ad7681e45e2b6d1f0680c9eb

Cherry-pick 'CheckCanRunGui' user command from patch 8.1.1826.

Problem:    When using valgrind a Vim command started by a test uses the same
            log file name which gets overwritten.
Solution:   Fix regexp to rename the log file.
https://github.com/vim/vim/commit/657a826c07b4ea3f8846b6acb2c50b82c2d81e50