vim-patch:8.2.4603: sourcing buffer lines is too complicated

Problem:    Sourcing buffer lines is too complicated.
Solution:   Simplify the code. Make it possible to source Vim9 script lines.
            (Yegappan Lakshmanan, closes vim/vim#9974)

85b43c6cb7

This commit changes the behavior of sourcing buffer lines to always have
a script ID, although sourcing the same buffer always produces the same
script ID.

vim-patch:9.1.0372: Calling CLEAR_FIELD() on the same struct twice

Problem:  Calling CLEAR_FIELD() on the same struct twice.
Solution: Remove the second CLEAR_FIELD().  Move the assignment of
          cookie.sourceing_lnum (zeertzjq).

closes: vim/vim#14627

f68517c167

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

test/functional/core/exit_spec.lua

@@ -97,14 +97,26 @@ describe(':cquit', function()
   end)
 
   it('exits with redir msg for multiple exit codes after :cquit 1 2', function()
-    test_cq('cquit 1 2', nil, 'nvim_exec2(): Vim(cquit):E488: Trailing characters: 2: cquit 1 2')
+    test_cq(
+      'cquit 1 2',
+      nil,
+      'nvim_exec2(), line 1: Vim(cquit):E488: Trailing characters: 2: cquit 1 2'
+    )
   end)
 
   it('exits with redir msg for non-number exit code after :cquit X', function()
-    test_cq('cquit X', nil, 'nvim_exec2(): Vim(cquit):E488: Trailing characters: X: cquit X')
+    test_cq(
+      'cquit X',
+      nil,
+      'nvim_exec2(), line 1: Vim(cquit):E488: Trailing characters: X: cquit X'
+    )
   end)
 
   it('exits with redir msg for negative exit code after :cquit -1', function()
-    test_cq('cquit -1', nil, 'nvim_exec2(): Vim(cquit):E488: Trailing characters: -1: cquit -1')
+    test_cq(
+      'cquit -1',
+      nil,
+      'nvim_exec2(), line 1: Vim(cquit):E488: Trailing characters: -1: cquit -1'
+    )
   end)
 end)