patch 8.1.1832: win_execute() does not work in other tab

Problem:    Win_execute() does not work in other tab. (Rick Howe)
Solution:   Take care of the tab. (closes #4792)
diff --git a/src/testdir/test_execute_func.vim b/src/testdir/test_execute_func.vim
index 81a67c0..f3d7e37 100644
--- a/src/testdir/test_execute_func.vim
+++ b/src/testdir/test_execute_func.vim
@@ -100,3 +100,12 @@
   call win_gotoid(otherwin)
   bwipe!
 endfunc
+
+func Test_win_execute_other_tab()
+  let thiswin = win_getid()
+  tabnew
+  call win_execute(thiswin, 'let xyz = 1')
+  call assert_equal(1, xyz)
+  tabclose
+  unlet xyz
+endfunc