vim-patch:9.1.0438: Wrong Ex command executed when :g uses '?' as delimiter (#28956)

Problem:  Wrong Ex command executed when :g uses '?' as delimiter and
          pattern contains escaped '?'.
Solution: Don't use "*newp" when it's not allocated (zeertzjq).

closes: vim/vim#14837

3074137542

test/old/testdir/test_global.vim

@@ -96,7 +96,16 @@ func Test_global_newline()
   close!
 endfunc
 
-func Test_wrong_delimiter()
+" Test :g with ? as delimiter.
+func Test_global_question_delimiter()
+  new
+  call setline(1, ['aaaaa', 'b?bbb', 'ccccc', 'ddd?d', 'eeeee'])
+  g?\??delete
+  call assert_equal(['aaaaa', 'ccccc', 'eeeee'], getline(1, '$'))
+  bwipe!
+endfunc
+
+func Test_global_wrong_delimiter()
   call assert_fails('g x^bxd', 'E146:')
 endfunc
 

test/old/testdir/test_substitute.vim

@@ -174,8 +174,8 @@ func Test_substitute_repeat()
   bwipe!
 endfunc
 
-" Test :s with ? as separator.
-func Test_substitute_question_separator()
+" Test :s with ? as delimiter.
+func Test_substitute_question_delimiter()
   new
   call setline(1, '??:??')
   %s?\?\??!!?g