[vim] Use /dev/tty as STDIN when using --height w/o explicit source

plugin/fzf.vim

@@ -428,7 +428,8 @@ function! s:execute(dict, command, use_height, temps) abort
     let command = escaped
   endif
   if a:use_height
-    call system(printf('tput cup %d > /dev/tty; tput cnorm > /dev/tty; %s 2> /dev/tty', &lines, command))
+    let stdin = has_key(a:dict, 'source') ? '' : '< /dev/tty'
+    call system(printf('tput cup %d > /dev/tty; tput cnorm > /dev/tty; %s %s 2> /dev/tty', &lines, command, stdin))
   else
     execute 'silent !'.command
   endif