[empathy] Don't show "Topic: " in tooltips if there is none

[Guillaume Desmottes <gdesmott src gnome org>]

commit 6be8487c6325e206fa9741d6c91a4c2420169e1b
Author: Will Thompson <will thompson collabora co uk>
Date:   Wed Sep 5 20:14:41 2012 -0400

    Don't show "Topic: " in tooltips if there is none
    
    I think I made this regress when I made Empathy understand the new
    Subject interface.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=683453

 src/empathy-chat-window.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/empathy-chat-window.c b/src/empathy-chat-window.c
index cc5d2e2..0c01617 100644
--- a/src/empathy-chat-window.c
+++ b/src/empathy-chat-window.c
@@ -964,7 +964,7 @@ chat_window_update_chat_tab_full (EmpathyChat *chat,
   if (!EMP_STR_EMPTY (status))
     append_markup_printf (tooltip, "\n<i>%s</i>", status);
 
-  if (subject)
+  if (!EMP_STR_EMPTY (subject))
     append_markup_printf (tooltip, "\n<b>%s</b> %s",
         _("Topic:"), subject);