vim-patch:8.1.0972: cannot switch from terminal window to next tabpage

Problem:    Cannot switch from terminal window to next tabpage.
Solution:   Make CTRL-W gt move to next tabpage.
72e83c1ae5

src/nvim/window.c

@@ -528,6 +528,9 @@ wingotofile:
       cmdmod.tab = tabpage_index(curtab) + 1;
       nchar = xchar;
       goto wingotofile;
+    case 't':                       // CTRL-W gt: go to next tab page
+      goto_tabpage((int)Prenum);
+      break;
 
     case 'e':
       if (curwin->w_floating || !ui_has(kUIMultigrid)) {

test/functional/normal/tabpage_spec.lua

@@ -0,0 +1,25 @@
+local helpers = require('test.functional.helpers')(after_each)
+
+local clear = helpers.clear
+local command = helpers.command
+local eq = helpers.eq
+local feed = helpers.feed
+local eval = helpers.eval
+
+describe('tabpage', function()
+  before_each(clear)
+
+  it('advances to the next page via <C-W>gt', function()
+    -- add some tabpages
+    command('tabnew')
+    command('tabnew')
+    command('tabnew')
+
+    eq(4, eval('tabpagenr()'))
+
+    feed('<C-W>gt')
+
+    eq(1, eval('tabpagenr()'))
+  end)
+end)
+