Problem:    Empty group in 'tabline' may cause using an invalid pointer.
Solution:   Set the group start position. (closes vim/vim#6505)
https://github.com/vim/vim/commit/f56c95fdad5af521887f8cd7bc15729b5355231d
(cherry picked from commit 9443d3994190943c2b9d8c4efefcf3de854ec7be)

(Credit: Zach Wegner, https://github.com/neovim/neovim/pull/11034)

Problem:    "precedes" in 'listchars' not used properly.
Solution:   Correctly handle the "precedes" char in list mode for long lines.
https://github.com/vim/vim/commit/bffba7f7042f6082e75b42484b15f66087b01941

These options were previously global. A global-local window option
behaves closer to a global option "per default" (i e with :set),
but still supports local behavior via :setl

Also this restores back-compat for nvim_set_option("fcs", ...)
which are currently broken on 0.4.x but worked in earlier versions

Problem:    Draw error when an empty group is removed from 'statusline'.
Solution:   Do not use highlighting from a removed group.
https://github.com/vim/vim/commit/dbe5d361feb65137099644329cf0ecfd4a945a14

Set the environment variables before changing $HOME
so that python,ruby can find user modules not in $HOME.

Reference:
- https://github.com/neovim/neovim/commit/7be7ec98a22451ec75ce5eb9284fa1722b53c697
- https://github.com/neovim/neovim/issues/10270#issuecomment-531516948

Problem:    Ruby converts v:true and v:false to a number.
Solution:   Use Qtrue and Qfalse instead. (Masataka Pocke Kuwabara,
            closes vim/vim#3259)
https://github.com/vim/vim/commit/d84b26a03b13cd816d80ff32b61e8de740d499ce

nvim does not support v:none.

Problem:    Preferred cursor column not set in interfaces.
Solution:   Set w_set_curswant when setting the cursor. (David Hotham,
            closes vim/vim#3060)
https://github.com/vim/vim/commit/53901442f37a59e5495165f91db5574c0b43ab04

This contains test_ruby changes only.
test_python changes were ported before.

These tests didn't pass in https://github.com/neovim/neovim/pull/9245

Problem:    Segmentation fault when Ruby throws an exception inside :rubyfile
            command.
Solution:   Use rb_protect() instead of rb_load_protect(). (ujihisa,
            closes vim/vim#2147, greywolf, closes vim/vim#2512, vim/vim#2511)
https://github.com/vim/vim/commit/37badc898b8d167e11553b6d05908ffd35928a6e