Allow devops to test own patches

Adds a step to checkout the code from the Gerrit review
instead of running from master.

Bug 824
Change-Id: Ic080454518b9388b94fb7aa28fd55cde72463448
Signed-off-by: beierl <mbeierl@vmware.com>

Jenkinsfile

+/* Copyright 2019 ETSI
+ *
+ * All Rights Reserved.
+ *
+ *   Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *   not use this file except in compliance with the License. You may obtain
+ *   a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ *   License for the specific language governing permissions and limitations
+ *   under the License.
+ */
+
 properties([
     parameters([
         string(defaultValue: env.BRANCH_NAME, description: '', name: 'GERRIT_BRANCH'),
@@ -13,6 +30,10 @@ properties([
 def devops_checkout() {
     dir('devops') {
         git url: "${PROJECT_URL_PREFIX}/osm/devops", branch: params.GERRIT_BRANCH
+        sh "git fetch origin ${params.GERRIT_REFSPEC}"
+        if (params.GERRIT_PATCHSET_REVISION.size() > 0 ) {
+           sh "git checkout -f ${params.GERRIT_PATCHSET_REVISION}"
+        }
     }
 }