vim-patch:8.0.0900: :tab options doesn't open a new tab page

Problem:    :tab options doesn't open a new tab page. (Aviany)
Solution:   Support the :tab modifier. (closes vim/vim#1960)
ab6c8587ba

src/nvim/ex_cmds2.c

@@ -2728,6 +2728,7 @@ void ex_packadd(exarg_T *eap)
 /// ":options"
 void ex_options(exarg_T *eap)
 {
+  vim_setenv("OPTWIN_CMD", cmdmod.tab ? "tab" : "");
   cmd_source((char_u *)SYS_OPTWIN_FILE, NULL);
 }