Removing the skip decorator as bug 1687044 was already resolved

Change-Id: Idbeabefd574e1af5d1e62b27f6c195caa3c9fb37
diff --git a/tempest/api/volume/test_volumes_extend.py b/tempest/api/volume/test_volumes_extend.py
index 54052ae..c0902e2 100644
--- a/tempest/api/volume/test_volumes_extend.py
+++ b/tempest/api/volume/test_volumes_extend.py
@@ -44,7 +44,6 @@
     @decorators.idempotent_id('86be1cba-2640-11e5-9c82-635fb964c912')
     @testtools.skipUnless(CONF.volume_feature_enabled.snapshot,
                           "Cinder volume snapshots are disabled")
-    @decorators.skip_because(bug='1687044')
     def test_volume_extend_when_volume_has_snapshot(self):
         volume = self.create_volume()
         self.create_snapshot(volume['id'])