patch 8.2.4844: <C-S-I> is simplified to <S-Tab>

Problem:    <C-S-I> is simplified to <S-Tab>.
Solution:   Do not simplify CTRL if there is also SHIFT. (closes #10313)
diff --git a/src/getchar.c b/src/getchar.c
index 2b1bbde..6d8697c 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -1634,7 +1634,7 @@
 {
     int c = c_arg;
 
-    if (*modifiers & MOD_MASK_CTRL)
+    if ((*modifiers & MOD_MASK_CTRL) && !(*modifiers & MOD_MASK_SHIFT))
     {
 	if ((c >= '`' && c <= 0x7f) || (c >= '@' && c <= '_'))
 	{
diff --git a/src/testdir/test_gui.vim b/src/testdir/test_gui.vim
index 4ae01b8..96723b6 100644
--- a/src/testdir/test_gui.vim
+++ b/src/testdir/test_gui.vim
@@ -1560,4 +1560,10 @@
   bw!
 endfunc
 
+func Test_gui_CTRL_V()
+  call feedkeys(":let g:str = '\<C-V>\<*C-S-I>\<C-V>\<*C-S-@>'\<CR>", 'tx')
+  call assert_equal('<C-S-I><C-S-@>', g:str)
+  unlet g:str
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index ab771fe..5540985 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4844,
+/**/
     4843,
 /**/
     4842,