patch 8.0.0172: command line window does not work

Problem:    The command selected in the command line window is not executed.
            (Andrey Starodubtsev)
Solution:   Save and restore the command line at a lower level. (closes #1370)

src/ex_getln.c

@@ -773,9 +773,7 @@ getcmdline(
 		/*
 		 * Open a window to edit the command line (and history).
 		 */
-		save_cmdline(&save_ccline);
 		c = ex_window();
-		restore_cmdline(&save_ccline);
 		some_key_typed = TRUE;
 	    }
 	}
@@ -6904,9 +6902,7 @@ ex_window(void)
     redraw_later(SOME_VALID);
 
     /* Save the command line info, can be used recursively. */
-    save_ccline = ccline;
+    save_cmdline(&save_ccline);
-    ccline.cmdbuff = NULL;
-    ccline.cmdprompt = NULL;
 
     /* No Ex mode here! */
     exmode_active = 0;
@@ -6953,7 +6949,7 @@ ex_window(void)
 # endif
 
     /* Restore the command line info. */
-    ccline = save_ccline;
+    restore_cmdline(&save_ccline);
     cmdwin_type = 0;
 
     exmode_active = save_exmode;

src/testdir/test_history.vim

@@ -87,3 +87,20 @@ function Test_History()
   call assert_equal(-1, histnr('abc'))
   call assert_fails('call histnr([])', 'E730:')
 endfunction
+
+function Test_Search_history_window()
+  new
+  call setline(1, ['a', 'b', 'a', 'b'])
+  1
+  call feedkeys("/a\<CR>", 'xt')
+  call assert_equal('a', getline('.'))
+  1
+  call feedkeys("/b\<CR>", 'xt')
+  call assert_equal('b', getline('.'))
+  1
+  " select the previous /a command
+  call feedkeys("q/kk\<CR>", 'x!')
+  call assert_equal('a', getline('.'))
+  call assert_equal('a', @/)
+  bwipe!
+endfunc

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    172,
 /**/
     171,
 /**/