Try to use pygerrit2 if it's available

Change-Id: I0fc5b8f3700a94cc431daf8fc4075ba330276871
diff --git a/_modules/gerrit.py b/_modules/gerrit.py
index 8a23a01..0cb25c9 100644
--- a/_modules/gerrit.py
+++ b/_modules/gerrit.py
@@ -43,7 +43,10 @@
 HAS_GERRIT = False
 try:
     from gerritlib import gerrit
-    import pygerrit.rest
+    try:
+        import pygerrit2.rest as pygerrit
+    except ImportError:
+        import pygerrit.rest
     HAS_GERRIT = True
 except ImportError:
     pass