Render preview window when the initial query fails to match

Only if preview template contains {q}

Fix #1452
Related #1307

src/terminal.go

@@ -1533,7 +1533,7 @@ func (t *Terminal) Loop() {
 
 	go func() {
 		var focused *Item
-		var version int64
+		var version int64 = -1
 		for {
 			t.reqBox.Wait(func(events *util.Events) {
 				defer events.Clear()

test/test_go.rb

@@ -1427,6 +1427,12 @@ class TestGoFZF < TestBase
     tmux.until { |lines| !lines[1].include?('foo') }
   end
 
+  def test_preview_q_no_match_with_initial_query
+    tmux.send_keys %(: | #{FZF} --preview 'echo foo {q}{q}' --query foo), :Enter
+    tmux.until { |lines| lines.match_count == 0 }
+    tmux.until { |lines| lines[1].include?('foofoo') }
+  end
+
   def test_no_clear
     tmux.send_keys "seq 10 | fzf --no-clear --inline-info --height 5 > #{tempname}", :Enter
     prompt = '>   < 10/10'