Support pagination in simplequery for Gerrit >=2.9

Starting with Gerrit 2.9 the pagination mechanism changed to using
offsets instead of sortkeys. For details please check the release
notes of 2.9:

https://gerrit-documentation.storage.googleapis.com/ReleaseNotes/ReleaseNotes-2.9.html#_rest_api.

In order to support both versions it is necessary to check for the
presence of moreChanges in the status line and then process the next
chunks either with the old or the new method.

Change-Id: Ieb54052debd07d86db66ef0f1d7ce1bdb42964b4
diff --git a/test-requirements.txt b/test-requirements.txt
index c68b2db..d461078 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -11,3 +11,4 @@
 testrepository>=0.0.17
 testtools>=0.9.32
 sphinxcontrib-programoutput
+mock