patch 8.2.3461: cannot distinguish Normal and Terminal-Normal mode

Problem:    Cannot distinguish Normal and Terminal-Normal mode.
Solution:   Make mode() return "nt" for Terminal-Normal mode. (issue #8856)

runtime/doc/eval.txt

@@ -8061,7 +8061,7 @@ mode([expr])	Return a string that indicates the current mode.
 		returned, otherwise only the first letter is returned.
 		Also see |state()|.
 
-		   n	    Normal, Terminal-Normal
+		   n	    Normal
 		   no	    Operator-pending
 		   nov	    Operator-pending (forced characterwise |o_v|)
 		   noV	    Operator-pending (forced linewise |o_V|)
@@ -8070,6 +8070,7 @@ mode([expr])	Return a string that indicates the current mode.
 		   niI	    Normal using |i_CTRL-O| in |Insert-mode|
 		   niR	    Normal using |i_CTRL-O| in |Replace-mode|
 		   niV	    Normal using |i_CTRL-O| in |Virtual-Replace-mode|
+		   nt	    Terminal-Normal (insert goes to Terminal-Job mode)
 		   v	    Visual by character
 		   V	    Visual by line
 		   CTRL-V   Visual blockwise

src/misc1.c

@@ -712,6 +712,10 @@ f_mode(typval_T *argvars, typval_T *rettv)
 	    buf[1] = 'i';
 	    buf[2] = restart_edit;
 	}
+#ifdef FEAT_TERMINAL
+	else if (term_in_normal_mode())
+	    buf[1] = 't';
+#endif
     }
 
     // Clear out the minor mode when the argument is not a non-zero number or

src/testdir/test_functions.vim

@@ -874,6 +874,14 @@ func Test_mode()
   call assert_equal('c-ce', g:current_modes)
   " How to test Ex mode?
 
+  if has('terminal')
+    term
+    call feedkeys("\<C-W>N", 'xt')
+    call assert_equal('n', mode())
+    call assert_equal('nt', mode(1))
+    call feedkeys("aexit\<CR>", 'xt')
+  endif
+
   bwipe!
   iunmap <F2>
   xunmap <F2>

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3461,
 /**/
     3460,
 /**/