clean_old option was duplicated on clean_empty

The --no-old option wouldn't work because the check was checking for
--no-empty, and --no-empty was disabling both checks. :)

Signed-off-by: Kevin Fenzi <kevin@scrye.com>

util/koji-sidetag-cleanup

@@ -190,7 +190,7 @@ def delete_tags(tags):
 
 def clean_empty(tags):
     # delete empty tags which are older than --empty-delay
-    if not options.clean_old:
+    if not options.clean_empty:
         return tags
     passed = []
     candidates = []