small unit test fix to ensure we clear out existing activity entries before our activity api test.

test/metabase/api/activity_test.clj

@@ -19,7 +19,8 @@
 ;  2. :user and :model_exists are hydrated
 
 ; NOTE: timestamp matching was being a real PITA so I cheated a bit.  ideally we'd fix that
-(expect-let [activity1 (db/ins Activity
+(expect-let [_         (korma.core/delete Activity)
+             activity1 (db/ins Activity
                          :topic     "install"
                          :details   {}
                          :timestamp (u/parse-iso8601 "2015-09-09T12:13:14.888Z"))