Adding a comment to show the backward compatibility.

We must be sure that people won't change this code, because we need to
care about backward compatibilty.

slapos/libnetworkcachetests.py

@@ -98,6 +98,7 @@ class TestNetworkcacheClient(LibNetworkCacheMixin):
     url = 'http://%s:%s' % (self.host, self.port)
     self.shacache_url = url + self.shacache_path
     self.shadir_url = url + self.shadir_path
+    # checking the backwards compatibilty
     self.nc = NetworkcacheClient(shacache=self.shacache_url,
                                  shadir=self.shadir_url)