Merged revisions 198251 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r198251 | seanbright | 2009-05-29 22:46:41 -0400 (Fri, 29 May 2009) | 8 lines
  
  Treat an empty FORWARD_CONTEXT the same way we treat a missing one.
  
  (closes issue #15056)
  Reported by: p_lindheimer
  Patches:
        05292009_bug15056.diff uploaded by seanbright (license 71)
  Tested by: p_lindheimer
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@198285 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_dial.c

@@ -746,6 +746,9 @@ static void do_forward(struct chanlist *o,
 		const char *forward_context;
 		ast_channel_lock(c);
 		forward_context = pbx_builtin_getvar_helper(c, "FORWARD_CONTEXT");
+		if (ast_strlen_zero(forward_context)) {
+			forward_context = NULL;
+		}
 		snprintf(tmpchan, sizeof(tmpchan), "%s@%s", c->call_forward, forward_context ? forward_context : c->context);
 		ast_channel_unlock(c);
 		stuff = tmpchan;