fix(runtime): source old color scheme in bundled color schemes (#26641)

Problem:
Bundled color schemes use `:hi clear` and only define Vim's highlight
groups. This results into Nvim-specific highlight groups using
definitions from Nvim's default color scheme, which are not always
linked to a Vim's highlight group.

Solution:
Restore links to Vim's highlight groups which were present before Nvim's
default color scheme update.

runtime/colors/blue.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'blue'
 
 let s:t_Co = &t_Co

runtime/colors/darkblue.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'darkblue'
 
 let s:t_Co = &t_Co

runtime/colors/delek.vim

@@ -10,7 +10,8 @@
 
 set background=light
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'delek'
 
 let s:t_Co = &t_Co

runtime/colors/desert.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'desert'
 
 let s:t_Co = &t_Co

runtime/colors/elflord.vim

@@ -9,7 +9,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'elflord'
 
 let s:t_Co = &t_Co

runtime/colors/evening.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'evening'
 
 let s:t_Co = &t_Co

runtime/colors/habamax.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'habamax'
 
 let s:t_Co = &t_Co

runtime/colors/industry.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'industry'
 
 let s:t_Co = &t_Co

runtime/colors/koehler.vim

@@ -9,7 +9,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'koehler'
 
 let s:t_Co = &t_Co

runtime/colors/lunaperche.vim

@@ -8,7 +8,8 @@
 
 " Generated by Colortemplate v2.2.3
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'lunaperche'
 
 let s:t_Co = &t_Co

runtime/colors/morning.vim

@@ -10,7 +10,8 @@
 
 set background=light
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'morning'
 
 let s:t_Co = &t_Co

runtime/colors/murphy.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'murphy'
 
 let s:t_Co = &t_Co

runtime/colors/pablo.vim

@@ -9,7 +9,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'pablo'
 
 let s:t_Co = &t_Co

runtime/colors/peachpuff.vim

@@ -10,7 +10,8 @@
 
 set background=light
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'peachpuff'
 
 let s:t_Co = &t_Co

runtime/colors/quiet.vim

@@ -8,7 +8,8 @@
 
 " Generated by Colortemplate v2.2.3
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'quiet'
 
 let s:t_Co = &t_Co

runtime/colors/retrobox.vim

@@ -8,7 +8,8 @@
 
 " Generated by Colortemplate v2.2.3
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'retrobox'
 
 let s:t_Co = &t_Co

runtime/colors/ron.vim

@@ -9,7 +9,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'ron'
 
 let s:t_Co = &t_Co

runtime/colors/shine.vim

@@ -10,7 +10,8 @@
 
 set background=light
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'shine'
 
 let s:t_Co = &t_Co

runtime/colors/slate.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'slate'
 
 let s:t_Co = &t_Co

runtime/colors/sorbet.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'sorbet'
 
 let s:t_Co = &t_Co

runtime/colors/torte.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'torte'
 
 let s:t_Co = &t_Co

runtime/colors/wildcharm.vim

@@ -8,7 +8,8 @@
 
 " Generated by Colortemplate v2.2.3
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'wildcharm'
 
 let s:t_Co = &t_Co

runtime/colors/zaibatsu.vim

@@ -10,7 +10,8 @@
 
 set background=dark
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'zaibatsu'
 
 let s:t_Co = &t_Co

runtime/colors/zellner.vim

@@ -10,7 +10,8 @@
 
 set background=light
 
-hi clear
+" hi clear
+source $VIMRUNTIME/colors/vim.lua " Nvim: revert to Vim default color scheme
 let g:colors_name = 'zellner'
 
 let s:t_Co = &t_Co

runtime/doc/news.txt

@@ -106,7 +106,8 @@ The following changes may require adaptations in user config or plugins.
   This also might result into some color schemes looking differently due to
   them relying on an implicit assumptions about how highlight groups are
   defined by default. To account for this, define all attributes of highlight
-  groups explicitly or use `:colorscheme vim` to restore previous definitions.
+  groups explicitly. Alternatively, use `:colorscheme vim` or
+  `:source $VIMRUNTIME/colors/vim.lua` to restore previous definitions.
 
 • 'termguicolors' is enabled by default when Nvim is able to determine that
   the host terminal emulator supports 24-bit color.

runtime/doc/vim_diff.txt

@@ -32,8 +32,9 @@ Defaults					            *nvim-defaults*
   ":syntax off" to |init.vim|.
 - Default color scheme has been updated. This can result in color schemes
   looking differently due to them relying on how highlight groups are defined
-  by default. Add ":colorscheme vim" to |init.vim| or your color scheme file to
+  by default. Add ":colorscheme vim" to |init.vim| or
-  restore the old default links and colors.
+  ":source $VIMRUNTIME/colors/vim.lua" to your color scheme file to restore
+  the old default links and colors.
 
 - 'autoindent' is enabled
 - 'autoread' is enabled (works in all UIs, including terminal)